Error analysis of energy-conservative BDF2-FE scheme for the 2D Navier-Stokes equations with variable density

In this paper, we present an error estimate of a second-order linearized finite element (FE) method for the 2D Navier-Stokes equations with variable density. In order to get error estimates, we first introduce an equivalent form of the original system. Later, we propose a general BDF2-FE method for solving this equivalent form, where the Taylor-Hood FE space is used for discretizing the Navier-Stokes equations and conforming FE space is used for discretizing density equation. We show that our scheme ensures discrete energy dissipation. Under the assumption of sufficient smoothness of strong solutions, an error estimate is presented for our numerical scheme for variable density incompressible flow in two dimensions. Finally, some numerical examples are provided to confirm our theoretical results.Comment: 22 pages, 1 figure

DNA methylation and regulatory elements during chicken germline stem cell differentiation

Funding for Open Access provided by the UMD Libraries' Open Access Publishing Fund.The production of germ cells in vitro would open important new avenues for stem biology and human medicine, but the mechanisms of germ cell differentiation are not well understood. The chicken, as a great model for embryology and development, was used in this study to help us explore its regulatory mechanisms. In this study, we reported a comprehensive genome-wide DNA methylation landscape in chicken germ cells, and transcriptomic dynamics was also presented. By uncovering DNA methylation patterns on individual genes, some genes accurately modulated by DNA methylation were found to be associated with cancers and virus infection, e.g., AKT1 and CTNNB1. Chicken-unique markers were also discovered for identifying male germ cells. Importantly, integrated epigenetic mechanisms were explored during male germ cell differentiation, which provides deep insight into the epigenetic processes associated with male germ cell differentiation and possibly improves treatment options to male infertility in animals and humans

Purifikacija i svojstva kolagenolitičke proteaze proizvedene s pomoću Bacillus cereus MBL13

A novel collagenase-producing bacterium has been isolated and identified as Bacillus cereus MBL13. From the culture supernatant of B. cereus MBL13 grown on bone collagen as the sole carbon and nitrogen source, an extracellular protease with novel property of hydrolyzing waste animal bones was purified. The molecular mass of the purified collagenolytic protease was estimated to be (38.0±1.5) kDa. As determined by amino acid analysis, it had high contents of asparagine, lysine and serine. The optimum temperature and pH for the collagenase activity were 40 °C and pH=8.0, respectively. The results of the effects of some metal ions, inhibitors and protein substrates suggested that the purified collagenolytic protease is a member of the metalloproteases. Type I collagen (the typical collagen in animal bone) was used as the substrate for determination of Michaelis-Menten kinetics. The obtained Km value was (1.31±0.05) g/L and the corresponding vmax value was (12.54±2.5) μmol/min. The study assumes that the collagenolytic protease purified from B. cereus MBL13 strain could be applied in the hydrolysis of waste animal bones.Izolirana je nova bakterija koja proizvodi kolagenazu, identificirana kao Bacillus cereus MBL13. Iz supernatanta kulture B. cereus MBL13, uzgojene na koštanom kolagenu kao izvoru ugljika i dušika, izdvojena je ekstracelularna proteaza sa sposobnošću razgradnje životinjskih kostiju. Procijenjena je molekularna masa pročišćene kolagenolitičke proteaze od (38,0±1,5) kDa. Analiziran je aminokiselinski sastav i utvrđeno da enzim sadržava veliku količinu asparagina, lizina i serina. Optimalna temperatura za aktivnost kolagenaze bila je 40 °C, a optimalna pH-vrijednost 8,0. Prema utjecaju iona metala, inhibitora i proteinskih supstrata na aktivnost enzima zaključeno je da enzim pripada u grupu metaloproteaza. Kolagen tipa I (tipični sastojak životinjskih kostiju) upotrijebljen je kao supstrat pri određivanju parametara Michaelis-Mentenove kinetike. Km vrijednost bila je (1,31±0,05) g/L, a vmax (12,54±2,5) μmol/min. Zaključeno je da se kolagenolitička proteaza izdvojena iz B. cereus MBL13 može upotrijebiti za razgradnju životinjskih kostiju

Purifikacija i svojstva kolagenolitičke proteaze proizvedene s pomoću Bacillus cereus MBL13

A novel collagenase-producing bacterium has been isolated and identified as Bacillus cereus MBL13. From the culture supernatant of B. cereus MBL13 grown on bone collagen as the sole carbon and nitrogen source, an extracellular protease with novel property of hydrolyzing waste animal bones was purified. The molecular mass of the purified collagenolytic protease was estimated to be (38.0±1.5) kDa. As determined by amino acid analysis, it had high contents of asparagine, lysine and serine. The optimum temperature and pH for the collagenase activity were 40 °C and pH=8.0, respectively. The results of the effects of some metal ions, inhibitors and protein substrates suggested that the purified collagenolytic protease is a member of the metalloproteases. Type I collagen (the typical collagen in animal bone) was used as the substrate for determination of Michaelis-Menten kinetics. The obtained Km value was (1.31±0.05) g/L and the corresponding vmax value was (12.54±2.5) μmol/min. The study assumes that the collagenolytic protease purified from B. cereus MBL13 strain could be applied in the hydrolysis of waste animal bones.Izolirana je nova bakterija koja proizvodi kolagenazu, identificirana kao Bacillus cereus MBL13. Iz supernatanta kulture B. cereus MBL13, uzgojene na koštanom kolagenu kao izvoru ugljika i dušika, izdvojena je ekstracelularna proteaza sa sposobnošću razgradnje životinjskih kostiju. Procijenjena je molekularna masa pročišćene kolagenolitičke proteaze od (38,0±1,5) kDa. Analiziran je aminokiselinski sastav i utvrđeno da enzim sadržava veliku količinu asparagina, lizina i serina. Optimalna temperatura za aktivnost kolagenaze bila je 40 °C, a optimalna pH-vrijednost 8,0. Prema utjecaju iona metala, inhibitora i proteinskih supstrata na aktivnost enzima zaključeno je da enzim pripada u grupu metaloproteaza. Kolagen tipa I (tipični sastojak životinjskih kostiju) upotrijebljen je kao supstrat pri određivanju parametara Michaelis-Mentenove kinetike. Km vrijednost bila je (1,31±0,05) g/L, a vmax (12,54±2,5) μmol/min. Zaključeno je da se kolagenolitička proteaza izdvojena iz B. cereus MBL13 može upotrijebiti za razgradnju životinjskih kostiju

Brief Announcement: Building Fast Recoverable Persistent Data Structures with Montage

The recent emergence of fast, dense, nonvolatile main memory suggests that certain long-lived data structures might remain in their natural, pointer-rich format across program runs and hardware reboots. Operations on such structures must be instrumented with explicit write-back and fence instructions to ensure consistency in the wake of a crash. Techniques to minimize the cost of this instrumentation are an active topic of current research. We present what we believe to be the first general-purpose approach to building buffered durably linearizable persistent data structures, and a system, Montage, to support that approach. Montage is built on top of the Ralloc nonblocking persistent allocator. It employs a slow-ticking epoch clock, and ensures that no operation appears to span an epoch boundary. If a crash occurs in epoch e, all work performed in epochs e and e-1 is lost, but all work from prior epochs is preserved. We describe the implementation of Montage, argue its correctness, and report on experiments confirming excellent performance for operations on queues, sets/mappings, and general graphs

Microlensing effect of charged spherically symmetric wormhole

We systematically investigate the microlensing effect of charged spherically symmetric wormhole, where the light source is remote from the throat. Remarkably, there will be at most three images by considering the charge part. We study all situations including three images, two images, and one image, respectively. The numerical result shows that the range of total magnification is from $10^5$ to $10^{-2}$ depending on various metrics. In the case of three images, there will be two maximal values of magnification (a peak, and a gentle peak) when the contribution via mass is much less than that of charge. However, we cannot distinguish the case that forms three images or only one image as the total magnification is of order $10^5$. Finally, our theoretical investigation could shed new light on exploring the wormhole with the microlensing effect.Comment: 10 pages, 9 figure