The disappearance of a narrow Mg II absorption system in quasar SDSS J165501.31+260517.4

In this letter, we present for the first time, the discovery of the disappearance of a narrow Mg II $\lambda\lambda2796,2803$ absorption system from the spectra of quasar SDSS J165501.31+260517.4 ($z_{\rm e}=1.8671$). This absorber is located at $z_{\rm abs} =1.7877$, and has a velocity offset of $8,423\rm ~km~s^{-1}$ with respect to the quasar. According to the velocity offset and the line variability, this narrow Mg II $\lambda\lambda2796,2803$ absorption system is likely intrinsic to the quasar. Since the corresponding UV continuum emission and the absorption lines of another narrow Mg II $\lambda\lambda2796,2803$ absorption system at $z_{\rm abs}=1.8656$ are very stable, we think that the disappearance of the absorption system is unlikely to be caused by the change in ionization of absorption gas. Instead, it likely arises from the motion of the absorption gas across the line of sight

A note on the growth factor in Gaussian elimination for generalized Higham matrices

The Higham matrix is a complex symmetric matrix A=B+iC, where both B and C are real, symmetric and positive definite and $\mathrm{i}=\sqrt{-1}$ is the imaginary unit. For any Higham matrix A, Ikramov et al. showed that the growth factor in Gaussian elimination is less than 3. In this paper, based on the previous results, a new bound of the growth factor is obtained by using the maximum of the condition numbers of matrixes B and C for the generalized Higham matrix A, which strengthens this bound to 2 and proves the Higham's conjecture.Comment: 8 pages, 2 figures; Submitted to MOC on Dec. 22 201

Antimicrobial Effects of Probiotics and Novel Probiotic-Based Approaches for Infectious Diseases

Probiotics are live microorganisms, which confer health benefits on host when administered in adequate amounts. Probiotics exert their beneficial effects by maintenance flora healthy, enhancement of mucosal barrier integrity and modulation of immune responses. Antimicrobial substances including bacteriocins, hydrogen peroxide, organic acids, and short-chain fatty acids (SCFAs) produced by probiotics allow them to inhibit mucosal and epithelial adherence of pathogens and compete for limiting resources, thus suppress the growth of bacterial and fungal pathogens. Probiotics effect the colonization of fungal pathogen Candida to host surfaces, suppress Candida growth and biofilm development in vitro. Clinical results have shown that some probiotics can reduce oral, vaginal, and enteric colonization of Candida, alleviate clinical signs and symptoms, and potentially reduce the incidence of invasive fungal infection. Therefore, probiotics may be potential antifungals for prevention and treatment of candidiasis

An improved startup mode using clutch coupling for in-wheel electric vehicle drives

By introducing a new type of clutch into the driveline system of an in-wheel drive electric vehicle, a flexible connection has been developed to replace the rigid one between the hub and the motor. The driving motor can realize variable idling, unlike the internal combustion engine, which needs a minimum rotational speed. This paper proposes a new startup method that utilizes the initial kinetic energy of the motor to achieve a smooth and fast acceleration of the wheel speed from zero to the expected motor speed. First, the powertrain system, including the driving motor, the clutch and the vehicle resistance, is modelled. Second, factors influencing the starting current and the jerk level during the starting process are investigated. In consequence, the idle speed can be interpreted as a tunable variable that determines the tradeoff between the torque capacity and the jerk level. Finally, simulation and experiments on a laboratory test rig are performed. The results validate that the proposed variable-idle speed control strategy has a lower jerk level and lower starting current when compared with those using a direct start under the same load condition

Biosynthesis of Vitamins by Probiotic Bacteria

Vitamins are important micronutrients that are often precursors to enzymes, which all living cells require to perform biochemical reactions. However, humans cannot produce many vitamins, so they have to be externally obtained. Using vitamin‐producing microorganisms could be an organic and marketable solution to using pseudo‐vitamins that are chemically produced, and could allow for the production of foods with higher levels of vitamins that could reduce unwanted side effects. Probiotic bacteria, as well as commensal bacteria found in the human gut, such as Lactobacillus and Bifidobacterium, can de novo synthesize and supply vitamins to human body. In humans, members of the gut microbiota are able to synthesize vitamin K, as well as most of the water‐soluble B vitamins, such as cobalamin, folates, pyridoxine, riboflavin, and thiamine