An analysis on the convergence of equal-time commutators and the closure of the BRST algebra in Yang-Mills theories

In renormalizable theories, we define equal-time commutators (ETC'S) in terms of the equal-time limit and investigate its convergence in perturbation theory. We find that the equal-time limit vanishes for amplitudes with the effective dimension d_{\em eff} \leq -2 and is finite for those with d_{\em eff} =-1 but without nontrivial discontinuity. Otherwise we expect divergent equal-time limits. We also find that, if the ETC's involved in verifying an Jacobi identity exist, the identity is satisfied. Under these circumstances, we show in the Yang-Mills theory that the ETC of the $0$ component of the BRST current with each other vanishes to all orders in perturbation theory if the theory is free from the chiral anomaly, from which we conclude that $[\, Q\,,\,Q\,]=0$, where $Q$ is the BRST charge. For the case that the chiral anomaly is not canceled, we use various broken Ward identities to show that $[\, Q\,,\,Q\,]$ is finite and $[\,Q\,,\,[\, Q\,,\,Q]\,]$ vanishes at the one-loop level and that they start to diverge at the two-loop level unless there is some unexpected cancellation mechanism that improves the degree of convergence.Comment: 35 page

2011-2012 Master Class - Jeffrey Khaner (Flute)

https://spiral.lynn.edu/conservatory_masterclasses/1069/thumbnail.jp

2011-2012 Dean\u27s Showcase No. 2

https://spiral.lynn.edu/conservatory_deansshowcase/1022/thumbnail.jp

Malnutrition Has No Effect on the Timing of Human Tooth Formation

The effect of nutrition on the timing of human tooth formation is poorly understood. Delays and advancements in dental maturation have all been reported as well as no effect. We investigated the effect of severe malnutrition on the timing of human tooth formation in a large representative sample of North Sudanese children. The sample (1102 males, 1013 females) consisted of stratified randomly selected healthy individuals in Khartoum, Sudan, aged 2-22 years using a cross-sectional design following the STROBE statement. Nutritional status was defined using WHO criteria of height and weight. Body mass index Z-scores and height for age Z-scores of ≤-2 (cut-off) were used to identify the malnourished group (N = 474) while the normal was defined by Z-scores of ≥0 (N = 799). Clinical and radiographic examination of individuals, with known ages of birth was performed including height and weight measurements. Mandibular left permanent teeth were assessed using eight crown and seven root established tooth formation stages. Mean age at entry and mean age within tooth stages were calculated for each available tooth stage in each group and compared using a t-test. Results show the mean age at entry and mean age within tooth stages were not significantly different between groups affected by severe malnutrition and normal children (p>0.05). This remarkable finding was evident across the span of dental development. We demonstrate that there is little measurable effect of sustained malnutrition on the average timing of tooth formation. This noteworthy finding supports the notion that teeth have substantial biological stability and are insulated from extreme nutritional conditions compared to other maturing body systems

Incidence and clinical outcomes of nosocomial infections in patients presenting with STEMI complicated by cardiogenic shock in the United States

OBJECTIVES: This study addresses the incidence, trends, and impact of nosocomial infections (NI) on the outcomes of patients admitted with ST-segment elevation myocardial infarction (STEMI) and cardiogenic shock (STEMI-CS) using the United States National Inpatient Sample (NIS) database. METHODS: We analyzed data from 105,184 STEMI-CS patients using the NIS database from the years 2005-2014. NI was defined as infections of more than or equal to three days, comprising of central line-associated bloodstream infection (CLABSI), urinary tract infection (UTI), hospital-acquired pneumonia (HAP), Clostridium difficile infection (CDI), bacteremia, and skin related infections. Outcomes of the impact of NI on STEMI-CS included in-hospital mortality, length of hospital stay (LOS) and costs. Significant associations of NI in patients admitted with STEMI-CS were also identified. RESULTS: Overall, 19.1% (20,137) of patients admitted with STEMI-CS developed NI. Trends of NI have decreased from 2005-2014. The most common NI were UTI (9.2%), followed by HAP (6.8%), CLABSI (1.5%), bacteremia (1.5%), skin related infections (1.5%), and CDI (1.3%). The strongest association of developing a NI was increasing LOS (7-9 days; OR: 1.99; 95% CI: 1.75-2.26; \u3e9 days; OR: 4.51; 95% CI: 4.04-5.04 compared to 4-6 days as reference). Increased mortality risk among patients with NI was significant, especially those with sepsis-associated NI compared to those without sepsis (OR: 2.95; 95% CI: 2.72-3.20). Patients with NI were found to be associated with significantly longer LOS and higher costs, irrespective of percutaneous mechanical circulatory support placement. CONCLUSIONS: NI were common among patients with STEMI-CS. Those who developed NI were at a greater risk of in-hospital mortality, increased LOS and costs