An Examination of the Factors and Characteristics that Contribute to the Success of Putnam Fellows

The William Lowell Putnam Mathematical Competition is an intercollegiate mathematics competition for students in the United States and Canada and is regarded as the most prestigious and challenging mathematics competition in North America (Alexanderson, 2004; AMS, 2020; Grossman, 2002; Reznick, 1994; Schoenfeld, 1985). Students who earn the five highest scores on the examination are named Putnam Fellows. Since its inception in 1938, only 306 individuals have won the competition and a select few have won multiple times. Clearly, being named a Putnam Fellow is a remarkable achievement and therefore, understanding the factors and characteristics that contribute to their success is important for students interested in mathematics and STEM-related fields. Twenty-five males who were named Putnam Fellows either four, three, or two times were recruited for the study. A 17-item questionnaire was created from various research sources (Campbell, 1996a, 1996b; Campbell & Wu, 1996; DeFranco, 1996), and used to collect information around four broad areas—personal experiences, formal educational experiences, the affective domain and the cognitive domain. Qualitative research techniques were used to analyze the data. The results indicated that four subcategories of personal experiences, five subcategories of formal educational experiences, seven subcategories involving the affective domain, and three subcategories of the cognitive domain all played an important role in the development of Putnam Fellows. Future research recommendations should examine the factors and characteristics of female Putnam winners and ways to promote and support them as well as the role that Pólya-like heuristics play in the development of Putnam winners

Computational Methods for Structural Mechanics and Dynamics, part 1

The structural analysis methods research has several goals. One goal is to develop analysis methods that are general. This goal of generality leads naturally to finite-element methods, but the research will also include other structural analysis methods. Another goal is that the methods be amenable to error analysis; that is, given a physical problem and a mathematical model of that problem, an analyst would like to know the probable error in predicting a given response quantity. The ultimate objective is to specify the error tolerances and to use automated logic to adjust the mathematical model or solution strategy to obtain that accuracy. A third goal is to develop structural analysis methods that can exploit parallel processing computers. The structural analysis methods research will focus initially on three types of problems: local/global nonlinear stress analysis, nonlinear transient dynamics, and tire modeling

Aeroelastic Sizing for High-Speed Research (HSR) Longitudinal Control Alternatives Project (LCAP)

The Longitudinal Control Alternatives Project (LCAP) compared three high-speed civil transport configurations to determine potential advantages of the three associated longitudinal control concepts. The three aircraft configurations included a conventional configuration with a layout having a horizontal aft tail, a configuration with a forward canard in addition to a horizontal aft tail, and a configuration with only a forward canard. The three configurations were aeroelastically sized and were compared on the basis of operational empty weight (OEW) and longitudinal control characteristics. The sized structure consisted of composite honeycomb sandwich panels on both the wing and the fuselage. Design variables were the core depth of the sandwich and the thicknesses of the composite material which made up the face sheets of the sandwich. Each configuration was sized for minimum structural weight under linear and nonlinear aeroelastic loads subject to strain, buckling, ply-mixture, and subsonic and supersonic flutter constraints. This report describes the methods that were used and the results that were generated for the aeroelastic sizing of the three configurations

Is a community still a community? Reviewing definitions of key terms in community ecology

Community ecology is an inherently complicated field, confounded by the conflicting use of fundamental terms. Nearly two decades ago, Fauth etal. (1996) demonstrated that imprecise language led to the virtual synonymy of important terms and so attempted to clearly define four keywords in community ecology; community, assemblage, guild, and ensemble. We revisit Fauth etal.\u27s conclusion and discuss how the use of these terms has changed over time since their review. An updated analysis of term definition from a selection of popular ecological textbooks suggests that definitions have drifted away from those encountered pre-1996, and slightly disagreed with results from a survey of 100 ecology professionals (comprising of academic professors, nonacademic PhDs, graduate and undergraduate biology students). Results suggest that confusion about these terms is still widespread in ecology. We conclude with clear suggestions for definitions of each term to be adopted hereafter to provide greater cohesion among research groups

Structural basis for conductance by the archaeal aquaporin AqpM at 1.68 Å

To explore the structural basis of the unique selectivity spectrum and conductance of the transmembrane channel protein AqpM from the archaeon Methanothermobacter marburgensis, we determined the structure of AqpM to 1.68-A resolution by x-ray crystallography. The structure establishes AqpM as being in a unique subdivision between the two major subdivisions of aquaporins, the water-selective aquaporins, and the water-plus-glycerol-conducting aquaglyceroporins. In AqpM, isoleucine replaces a key histidine residue found in the lumen of water channels, which becomes a glycine residue in aquaglyceroporins. As a result of this and other side-chain substituents in the walls of the channel, the channel is intermediate in size and exhibits differentially tuned electrostatics when compared with the other subfamilies

Strain analysis of Ge micro disk using precession electron diffraction

The recently developed precession electron diffraction (PED) technique in scanning transmission electron microscopy has been used to elucidate the local strain distribution and crystalline misorientation in a CMOS fabricated strained Ge microdisk structure grown on a Si substrate. Tensile strained Ge and GeSn structures are considered to be potential CMOS compatible optical sources, as both Sn alloying and strain can lead to a direct band-structure and lasing. The ability to take nanometer resolution, experimental measurements of the cross-sectional strain distribution, is important to understand modal gain and, therefore, ultimate device performance. In this work, we demonstrate PED techniques to measure the cross-sectional strain field in tensile Ge microdisks strained by SiN stressors. The strain maps are interpreted and compared with a finite element model of the strain in the investigated structure, which shows good agreement, and, therefore, highlights the applicability of PED techniques for mapping strained photonic structures. The technique also allows for the observation of strain relaxation due to dislocation pileup, further demonstrating the benefit of such experimental techniques

Progressive induction of left ventricular pressure overload in a large animal model elicits myocardial remodeling and a unique matrix signature

ObjectivePatients with severe left ventricular pressure overload secondary to aortic stenosis can present with signs and symptoms of heart failure despite normal left ventricular ejection fraction. This process occurs, at least in part, as a result of left ventricular pressure overload–induced extracellular matrix remodeling that promulgates increased left ventricular stiffness and impaired diastolic function. However, the determinants that drive extracellular matrix remodeling in this form of left ventricular pressure overload remain to be fully defined.MethodsLeft ventricular pressure overload was induced in mature pigs (n = 15) by progressive ascending aortic cuff inflation (once per week for 4 weeks), whereby left ventricular mass, left ventricular ejection fraction, and regional myocardial stiffness (rKm) were compared with referent controls (n = 12). Determinants of extracellular matrix remodeling were assessed by measuring levels of mRNA expression for fibrillar collagens, matrix metalloproteinases, and tissue inhibitors of matrix metalloproteinase 1 and 4.ResultsWith left ventricular pressure overload, left ventricular mass and rKm increased by 2- and 3-fold, respectively, compared with control, with no change in left ventricular ejection fraction. Left ventricular myocardial collagen increased approximately 2-fold, which was accompanied by reduced solubility (ie, increased cross-linking) with left ventricular pressure overload, but mRNA expression for fibrillar collagen and matrix metalloproteinases remained relatively unchanged. In contrast, a robust increase in mRNA expression for tissue inhibitors of matrix metalloproteinase-1 and 4 occurred with left ventricular pressure overload.ConclusionsIn a progressive model of left ventricular pressure overload, which recapitulates the phenotype of aortic stenosis, increased extracellular matrix accumulation and subsequently increased myocardial stiffness were not due to increased fibrillar collagen expression but rather to determinants of post-translational control that included increased collagen stability (thereby resistant to matrix metalloproteinase degradation) and increased endogenous matrix metalloproteinase inhibition. Targeting these extracellular matrix post-translational events with left ventricular pressure overload may hold both diagnostic and therapeutic relevance