Quinoxaline polymers and copolymers derived from 1, 4-BIS(1'-napthalenyloxayl) benzene

A route for the synthesis of a new monomer, 1,4-bis(1'-naphthalenyl)-oxayl benzene, was devised, and six polymers and copolymers were prepared from this monomer, 1,4-bis(phenyloaxaly)benzene, 3,3'-diaminobenzidine and 3,3',4,4'-tetraaminobenzophenone. Thermogravimetric analysis showed that decomposition of these quinoxaline polymers and copolymers sets in at about 500 C but does not become significant in an inert atmosphere below 600 C. Oxidation becomes significant at about 550 C and the phenylquinoxaline homopolymer is somewhat more oxidation resistant than is the 1-naphthalenylquinoxaline homopolymer. Stress-relaxation measurements showed that, with two exceptions, the homopolymers and copolymers exhibited two second-order transition temperatures, one at about 204.4 C (400 F) and the other at about 315.6 C (600 F). No gross differences in the high temperature plasticity was observed between the naphthalenyl- and the phenyl-quinoaxaline homopolymers. Work was begun on a method for cross-linking polyquinoxalines. A new monomer, p-(methyloxaly)benzil, was synthesized, and model reaction studies showed that cross-linking of 2-methylquinoxaline polymers by a Michael condensation with dimaleimides will probably occur

SpxA1 and SpxA2 act coordinately to fine-tune stress responses and virulence in Streptococcus pyogenes

SpxA is a unique transcriptional regulator highly conserved among members of the phylum Firmicutes that binds RNA polymerase and can act as an antiactivator. Why some Firmicutes members have two highly similar SpxA paralogs is not understood. Here, we show that the SpxA paralogs of the pathogen Streptococcus pyogenes, SpxA1 and SpxA2, act coordinately to regulate virulence by fine-tuning toxin expression and stress resistance. Construction and analysis of mutants revealed that SpxA1− mutants were defective for growth under aerobic conditions, while SpxA2− mutants had severely attenuated responses to multiple stresses, including thermal and oxidative stresses. SpxA1− mutants had enhanced resistance to the cationic antimicrobial molecule polymyxin B, while SpxA2− mutants were more sensitive. In a murine model of soft tissue infection, a SpxA1− mutant was highly attenuated. In contrast, the highly stress-sensitive SpxA2− mutant was hypervirulent, exhibiting more extensive tissue damage and a greater bacterial burden than the wild-type strain. SpxA1− attenuation was associated with reduced expression of several toxins, including the SpeB cysteine protease. In contrast, SpxA2− hypervirulence correlated with toxin overexpression and could be suppressed to wild-type levels by deletion of speB. These data show that SpxA1 and SpxA2 have opposing roles in virulence and stress resistance, suggesting that they act coordinately to fine-tune toxin expression in response to stress. SpxA2− hypervirulence also shows that stress resistance is not always essential for S. pyogenes pathogenesis in soft tissue

Where Have all the Patent Lawyers Gone? Long Time Passing...

This article pursues two distinct, but related hypotheses. First, as total LSAT takers decline, we expect to see a decline in the number of new attorneys admitted to the patent bar. Second, as the number of new patent attorneys shrinks and the number of women pursuing engineering degrees increases, we expect that the patent bar will become more female. In order to test these hypotheses, we gathered and collated data from the Law School Admission Counsel (LSAC) regarding students taking the Law School Admissions Test (LSAT), the United States Patent and Trademark Office (USPTO), the Society of Women Engineers (SWE), and the American Bar Association (ABA). The data establishes that the first hypothesis is true, but the second one is false. That is, the number of new entrants to the patent bar will drop precipitously. By 2018, new entrants will number one half of what they were in 2008. However, the number of female patent attorneys compared to the number of male patent attorneys will not change in this same time period. That is, even though the patent bar will shrink, the patent bar will not become more female

Where Have all the Patent Lawyers Gone? Long Time Passing...

This article pursues two distinct, but related hypotheses. First, as total LSAT takers decline, we expect to see a decline in the number of new attorneys admitted to the patent bar. Second, as the number of new patent attorneys shrinks and the number of women pursuing engineering degrees increases, we expect that the patent bar will become more female. In order to test these hypotheses, we gathered and collated data from the Law School Admission Counsel (LSAC) regarding students taking the Law School Admissions Test (LSAT), the United States Patent and Trademark Office (USPTO), the Society of Women Engineers (SWE), and the American Bar Association (ABA). The data establishes that the first hypothesis is true, but the second one is false. That is, the number of new entrants to the patent bar will drop precipitously. By 2018, new entrants will number one half of what they were in 2008. However, the number of female patent attorneys compared to the number of male patent attorneys will not change in this same time period. That is, even though the patent bar will shrink, the patent bar will not become more female

Everything is connected: network thinking in entomology

Editorial

Comparison of mortality with home hemodialysis and center hemodialysis: A national study

Comparison of mortality with home hemodialysis and center hemodialysis: A national study. We sought to determine whether lower mortality rates reported with hemodialysis (HD) at home compared to hemodialysis in dialysis centers (center HD) could be explained by patient selection. Data are from the United States Renal Data System (USRDS) Special Study Of Case Mix Severity, a random national sample of 4,892 patients who started renal replacement therapy in 1986 to 1987. Intent-to-treat analyses compared mortality between home HD (N =70) and center HD patients (N = 3,102) using the Cox proportional hazards model. Home HD patients were younger and had a lower frequency of comorbid conditions. The unadjusted relative risk (RR) of death for home HD patients compared to center HD was 0.37 (P < 0.001). The RR adjusted for age, sex, race and diabetes, was 44% lower in home HD patients (RR = 0.56, P = 0.02). When additionally adjusted for comorbid conditions, this RR increased marginally (RR = 0.58, P = 0.03). A different analysis using national USRDS data from 1986/7 and without comorbid adjustment showed patients with training for self care hemodialysis at home or in a center (N = 418) had a lower mortality risk (RR = 0.78, P = 0.001) than center HD patients (N = 43,122). Statistical adjustment for comorbid conditions in addition to age, sex, race, and diabetes explains only a small amount of the lower mortality with home HD

How to salvage a salvage endoprosthesis.

Custom-made endoprostheses can be linked to existing well-fixed implants in the treatment of complex periprosthetic femoral fractures. By adopting this salvage approach, secure implants can be retained in favour of patients undergoing more tissue disruptive procedures such as total femoral replacements. In this piece, we present a unique case illustrating a salvage strategy for treating a failed cement-linked salvage endoprosthesis, a complex scenario which to our knowledge has never before been reported

A Probabilistic proof of the breakdown of Besov regularity in LL-shaped domains

{We provide a probabilistic approach in order to investigate the smoothness of the solution to the Poisson and Dirichlet problems in $L$-shaped domains. In particular, we obtain (probabilistic) integral representations for the solution. We also recover Grisvard's classic result on the angle-dependent breakdown of the regularity of the solution measured in a Besov scale