Effect of Notches on the Axial Fatigue Properties of Structural Steels

The effect of the stress concentration on the zero-to-tension axial fatigue strength of notched members of four structural steels has been studied. For each of the four steels a critical notch severity was found at which a transition in behavior takes place. When the theoretical stress concentration exceeds this critical value the fatigue strength increases instead of continuing to decrease as would normally be expected. The maximum effective stress concentration determined from these tests corresponds to a critical notch severity which is dependent on the material) the geometry of the specimen) and the cyclic conditions of stress. Microscopic examinations of the roots of the notched specimens which did not fail revealed cracking in most cases. Some of the cracks apparently were nonpropagating cracks but the test lives in most cases were insufficient to isolate such cracks positively as non-propagating. A study of other data on non-propagating cracks revealed that the laws governing their formation are not yet fully understood. However, there are indications that the increase in fatigue strength obtained above the critical notch severity is coincident with the formation of non~propagating cracks.The Engineering FoundationAmerican Iron and Steel InstituteChicago Bridge and Iron FoundationThe Welding Research Counci

Fatigue and Static Properties of Welded Joints in Low Alloy Structural Steels

Ohio River Division LaboratoriesCorps of Engineers, U.S. Army.Contract No. DA-33-eng-25

Emerging Visions for Sustainable Urbanization

Harsh critiques of the utopian visions of modernist architects have led many of today's designers to seek to fit their constructed responses into the mainstream culture (Schneekloth, 1998). While undoubtedly the works of most designers are grounded in the intention of making the world a better and more beautiful place, the underlying desire to fit in with the mainstream leads implicitly to confirming the status quo of the built environment. We believe that if designers are to move toward envisioning and creating more sustainable urban futures they must eschew the desire to fit in and carefully and methodically reconsider what is possible. To that end, in this paper we explore the motivations, methods and outcomes of five students in their penultimate design studio of the Masters of Architecture program at the University of Illinois at Urbana-Champaign. Using three measures, motivations, methods, and outcomes, as evidence we seek to understand how future designers, as they complete their education and embark on careers in the design professions, comprehend and envision an urbanization process that results in a sustainable urban future

Issues in maintaining a sister-school coaching collaborative

The implementation of coaching as a form of professional development for classroom teachers is becoming more and more accepted. Knight (2009a) reminds us, "what coaching offers is authentic learning that provides differentiated support for professional learning" (p. 2). Approached from a sociocultural foundation of communities of practice (Wenger, 1998a) this research study provides a lens into the practice of three elementary school instructional coaches working together as a collaborative unit. This work offers an in-depth understanding of how outside factors influenced the coaches’ negotiation of the multiple roles and responsibilities of their position. A case study approach was used in this year-long qualitative research project, focusing on the collaborative work of instructional coaches. In this study the researcher positioned herself as a potential change agent, approaching the research from an insider position. The three coaches in this study worked together in a collaborative coaching unit, conceived of and created by their district administration. Each coach was housed on a daily basis in her own elementary building. Throughout the first year of the coaching collaborative coaches were responsible for providing professional development, focused on literacy instruction, to K-3 classroom teachers from the coaches' respective home schools. During the year of this study coaches' roles and responsibilities shifted as the district adopted new math and ELA curriculum and outside consultants became responsible for the professional development K-5. At the same time coaches’ focus on classroom instruction shifted significantly to support student testing as the district implemented a new nationally normed testing screener, as well as the Partnership for Assessment of Readiness for College and Careers (PARCC) test. Ultimately these outside factors, in addition to multiple interpretations of the coaching position by administration, affected the coaches' ability to define their identity as coaches and as a collaborative unit. This study shifts the focus of current coaching research from a results-based/outcomes approach to a focus on who coaches are as professionals, how they navigate outside influences, and the subsequent development of their identities as coaches. The implications call for understanding the need for instructional coaches to have access to collaborative processes that are both casual and formal. The study suggests that opportunities for coaches to convene on a regular basis to develop their coaching practice from a professional learning community (DuFour, 2004) stance would be beneficial on multiple levels. Additionally, this work revealed the need for coaches to gather on an informal basis to share coaching stories and offer support to one another. This new perspective on instructional coaching offers important information into the professional needs of coaches and ways in which administration can support their work

Obesity in psoriasis: leptin and resistin as mediators of cutaneous inflammation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72152/1/j.1365-2133.2008.08655.x.pd

Electron Cryotomography of Bacterial Secretion Systems

In biology, function arises from form. For bacterial secretion systems, which often span two membranes, avidly bind to the cell wall, and contain hundreds of individual proteins, studying form is a daunting task, made possible by electron cryotomography (ECT). ECT is the highest-resolution imaging technique currently available to visualize unique objects inside cells, providing a three-dimensional view of the shapes and locations of large macromolecular complexes in their native environment. Over the past 15 years, ECT has contributed to the study of bacterial secretion systems in two main ways: by revealing intact forms for the first time and by mapping components into these forms. Here we highlight some of these contributions, revealing structural convergence in type II secretion systems, structural divergence in type III secretion systems, unexpected structures in type IV secretion systems, and unexpected mechanisms in types V and VI secretion systems. Together, they offer a glimpse into a world of fantastic forms—nanoscale rotors, needles, pumps, and dart guns—much of which remains to be explored

First report on an inotropic peptide activating tetrodotoxin-sensitive, "neuronal" sodium currents in the heart

Background— New therapeutic approaches to improve cardiac contractility without severe risk would improve the management of acute heart failure. Increasing systolic sodium influx can increase cardiac contractility, but most sodium channel activators have proarrhythmic effects that limit their clinical use. Here, we report the cardiac effects of a novel positive inotropic peptide isolated from the toxin of the Black Judean scorpion that activates neuronal tetrodotoxin-sensitive sodium channels. Methods and Results— All venoms and peptides were isolated from Black Judean Scorpions (Buthotus Hottentotta) caught in the Judean Desert. The full scorpion venom increased left ventricular function in sedated mice in vivo, prolonged ventricular repolarization, and provoked ventricular arrhythmias. An inotropic peptide (BjIP) isolated from the full venom by chromatography increased cardiac contractility but did neither provoke ventricular arrhythmias nor prolong cardiac repolarization. BjIP increased intracellular calcium in ventricular cardiomyocytes and prolonged inactivation of the cardiac sodium current. Low concentrations of tetrodotoxin (200 nmol/L) abolished the effect of BjIP on calcium transients and sodium current. BjIP did not alter the function of Nav 1.5 , but selectively activated the brain-type sodium channels Nav 1.6 or Nav 1.3 in cellular electrophysiological recordings obtained from rodent thalamic slices. Nav 1.3 (SCN3A) mRNA was detected in human and mouse heart tissue. Conclusions— Our pilot experiments suggest that selective activation of tetrodotoxin-sensitive neuronal sodium channels can safely increase cardiac contractility. As such, the peptide described here may become a lead compound for a new class of positive inotropic agents. </jats:sec

An International Multi-Center Evaluation of Type 5 Long QT Syndrome: A Low Penetrant Primary Arrhythmic Condition.

Background: Insight into type 5 long QT syndrome (LQT5) has been limited to case reports and small family series. Improved understanding of the clinical phenotype and genetic features associated with rare KCNE1 variants implicated in LQT5 was sought through an international multi-center collaboration. Methods: Patients with either presumed autosomal dominant LQT5 (N = 229) or the recessive Type 2 Jervell and Lange-Nielsen syndrome (JLNS2, N = 19) were enrolled from 22 genetic arrhythmia clinics and 4 registries from 9 countries. KCNE1 variants were evaluated for ECG penetrance (defined as QTc > 460ms on presenting ECG) and genotype-phenotype segregation. Multivariable Cox regression was used to compare the associations between clinical and genetic variables with a composite primary outcome of definite arrhythmic events, including appropriate implantable cardioverter-defibrillator shocks, aborted cardiac arrest, and sudden cardiac death. Results: A total of 32 distinct KCNE1 rare variants were identified in 89 probands and 140 genotype positive family members with presumed LQT5 and an additional 19 JLNS2 patients. Among presumed LQT5 patients, the mean QTc on presenting ECG was significantly longer in probands (476.9 ± 38.6ms) compared to genotype positive family members (441.8 ± 30.9ms, p<0.001). ECG penetrance for heterozygous genotype positive family members was 20.7% (29/140). A definite arrhythmic event was experienced in 16.9% (15/89) of heterozygous probands in comparison with 1.4% (2/140) of family members (adjusted hazard ratio [HR]: 11.6, 95% confidence interval [CI]: 2.6-52.2; p=0.001). Event incidence did not differ significantly for JLNS2 patients relative to the overall heterozygous cohort (10.5% [2/19]; HR: 1.7, 95% CI: 0.3-10.8, p=0.590). The cumulative prevalence of the 32 KCNE1 variants in the Genome Aggregation Database (gnomAD), which is a human database of exome and genome sequencing data from now over 140,000 individuals, was 238-fold greater than the anticipated prevalence of all LQT5 combined (0.238% vs. 0.001%). Conclusions: The present study suggests that putative/confirmed loss-of-function KCNE1 variants predispose to QT-prolongation, however the low ECG penetrance observed suggests they do not manifest clinically in the majority of individuals, aligning with the mild phenotype observed for JLNS2 patients