143,302 research outputs found
Remark on a Paper of Yu on Heilbronn's Exponential Sum
AbstractWe show that Sh(a)=∑pn=1e(anhp/p2)⪡(h, p−1)11/16p7/8, sharpening a result of Yu
Recommended from our members
A novel antibacterial peptide derived from Crocodylus siamensis haemoglobin hydrolysate induces membrane permeabilization causing iron dysregulation, oxidative stress and bacterial death
Aims
A novel antibacterial peptide from Crocodylus siamensis haemoglobin hydrolysate (CHH) was characterized for antimicrobial activity.
Methods and Results
CHHs were hydrolysed for 2 h (2 h-CHH), 4 h (4h-CHH), 6 h (6 h-CHH) and 8 h (8 h-CHH). The 8 h-CHH showed antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa at concentrations of 20, 20, 20 and 10 mg ml−1 (w/v) respectively. Fluorescent microscopy revealed that the 8 h-CHH had bactericidal activity against E. coli and P. aeruginosa. β-galactosidase assay supported by RT-qPCR demonstrated that the 8 h-CHH resulted in differential expression of genes involved in iron homeostasis (ftnA and bfd) and oxidative stress (sodA, soxR and oxyR). Siderophore assay indicated that the 8 h-CHH also impaired siderophore production with diminished expression of pvdF. This pattern of gene expression suggests that the 8 h-CHH triggers the release of free ferric ions in the cytoplasm. However, decreased expression of genes associated with the SOS response (recA and lexA) in combination with neutral comet revealed that no DNA damage was caused by 8 h-CHH. Membrane permeabilization assay indicated that 8 h-CHH caused membrane leakage thought to mediate the antibacterial and iron-stress responses observed, due to loss of regulated iron transport. The novel active peptide from 8 h-CHH was determined as QAIIHNEKVQAHGKKVL (QL17), with 41% hydrophobicity and +2 net charge.
Conclusions
The QAIIHNEKVQAHGKKVL fragment of C. siamensis haemoglobin is antibacterial via a mechanism that likely relies on iron dysregulation and oxidative stress which results in bacterial death.
Significance and Impact of the Study
We have described for the first time, a novel peptide derived from C. siamensis haemoglobin hydrolysate that has the potential to be developed as a novel antimicrobial peptide
Producing innovation: Comments on Lee and Yu (2010)
The purpose of the article being reviewed (Lee and Yu, 2010), a survey by questionnaire with 182 valid responses, is to analyze “how different relationship styles of employees in the hi-tech industry influence innovation performance” and indeed its conclusions are that “the relationship style of an organization has a significant positive effect on innovation performance”. We see Lee and Yu (2010) as being similar to another highly cited article by Morgan and Hunt in so far as both articles are about relationships, cooperation and trust
Reply to "Comment on 'Topological stability of the half-vortices in spinor exciton-polariton condensates'"
In a recent work [H. Flayac, I.A. Shelykh, D.D. Solnyshkov and G. Malpuech,
Phys. Rev. B 81, 045318 (2010)], we have analyzed the effect of the TE-TM
splitting on the stability of the exciton-polariton vortex states. We
considered classical vortex solutions having cylindrical symmetry and we found
that the so-called half-vortex states [Yu. G. Rubo, Phys. Rev. Lett. 99, 106401
(2007)] are not solutions of the stationary Gross-Pitaevskii equation. In their
Comment [M. Toledo Solano, Yu.G. Rubo, Phys. Rev. B 82, 127301 (2010)], M.
Toledo Solano and Yuri G. Rubo claim that this conclusion is misleading and
pretend to demonstrate the existence of static half-vortices in an
exciton-polariton condensate in the presence of TE-TM splitting. In this reply
we explain why this assertion is not demonstrated satisfactorily.Comment: 3 Pages, no figur
Triangles in graphs without bipartite suspensions
Given graphs and , the generalized Tur\'an number ex is the
maximum number of copies of in an -vertex graph with no copies of .
Alon and Shikhelman, using a result of Erd\H os, determined the asymptotics of
ex when the chromatic number of is greater than 3 and proved
several results when is bipartite. We consider this problem when has
chromatic number 3. Even this special case for the following relatively simple
3-chromatic graphs appears to be challenging.
The suspension of a graph is the graph obtained from by
adding a new vertex adjacent to all vertices of . We give new upper and
lower bounds on ex when is a path, even cycle, or
complete bipartite graph. One of the main tools we use is the triangle removal
lemma, but it is unclear if much stronger statements can be proved without
using the removal lemma.Comment: New result about path with 5 edges adde
- …