Differences in Bacterial Communities on Decaying Leaf Litter of Different Tress in Response to Burning as a Forest Restoration Technique

Decomposition is the process by which organic matter gets degraded into basic components to provide energy for decomposer microorganisms and to also make nutrients available for plant uptake. Leaf litter decomposition is an important process and influences the nutrient cycling and the productivity and structure of the entire ecosystem; however, few studies have examined the bacterial communities on decomposing litter, especially how they may vary between tree species or in woodlands subject to ecological restoration. Such restoration has become important, as fire suppression beginning in the 1920s has impacted the structure of forest ecosystems through the process of mesophication, diminishing the abundance of fire-dependent species and favoring more shade-tolerant, fire-intolerant trees. These changes likely influence the composition of the litter microbial community. This study used next generation sequencing of 16S rRNA genes to characterize the bacterial communities on litter from six different tree species, including representatives of upland oak woodlands (oaks) and mesophytic species (non-oaks), in a north Mississippi forest undergoing restoration. Results suggest that the bacterial community on leaf litter changes significantly as decomposition proceeds, and that there are differences in bacterial communities present on litter from oak versus non-oak species. Comparing the bacterial communities on leaf litter collected from a site that experienced a prescribed burn within the collection year, to a non-burned site suggested that fire did affect the bacterial community present on the decaying leaf litter. Together, these results indicate that both ecological restoration (fire) and the effects of restoration (a change in tree species) are likely to influence the composition of the litter bacterial community

Effect of Reynolds number variation on aerodynamics of a hydrogen-fueled transport concept at Mach 6

Two separate tests have been made on the same blended wing-body hydrogen-fueled transport model at a Mach number of about 6 and a range of Reynolds number (based on theoretical body length) of 1.577 to 55.36 X 10 to the 6th power. The results of these tests, made in a conventional hypersonic blowdown tunnel and a hypersonic shock tunnel, are presented through a range of angle of attack from -1 to 8 deg, with an extended study at a constant angle of attack of 3 deg. The model boundary layer flow appeared to be predominately turbulent except for the low Reynolds number shock tunnel tests. Model wall temperatures varied considerably; the blowdown tunnel varied from about 255 F to 340 F, whereas the shock tunnel had a constant 70 F model wall temperature. The experimental normal-force coefficients were essentially independent of Reynolds number. A current theoretical computer program was used to study the effect of Reynolds number. Theoretical predictions of normal-force coefficients were good, particularly at anticipated cruise angles of attack, that is 2 to 5 deg. Axial-force coefficients were generally underestimated for the turbulent skin friction conditions, and pitching-moment coefficients could not be predicted reliably

A parametric study of effect of forebody shape on flow angularity at Mach 8

Flow angularity and static pressure measurements have been made on the lower surface of nine forebody models that simulate the bottom forward surface of a hypersonic aircraft. Measurements were made in an area of the forebody that represents the location of an inlet of a scramjet engine. A parametric variation of the forebody surface investigated the effect of: (1) spanwise curvature; (2) longitudinal curvature; and (3) planform shape on both flow angularity and static pressure distribution. Results of each of the three parametric variations of geometry were compared to those for the same flat delta forebody. Spanwise curvature results showed that a concave shape and the flat delta had the lowest flow angularity and lowest rate of increase in flow angularity with angle of attack. Longitudinal curvature results showed a convex surface to give the better flow at the higher angles of attack. The better of the two planform shapes tested was a convex elliptical shape. Limited flow field calculations were made at angles of attack using a three dimensional, method-of-characteristics program. In general, at all angles of attack there was agreement between data and theory

Gaussian multiplicative chaos through the lens of the 2D Gaussian free field

The aim of this review-style paper is to provide a concise, self-contained and unified presentation of the construction and main properties of Gaussian multiplicative chaos (GMC) measures for log-correlated fields in 2D in the subcritical regime. By considering the case of the 2D Gaussian free field, we review convergence, uniqueness and characterisations of the measures; revisit Kahane's convexity inequalities and existence and scaling of moments; discuss the measurability of the underlying field with respect to the GMC measure and present a KPZ relation for scaling exponents.Comment: 28p, less typos in the 3rd, published version, still no figures, I remain thankful for comment

Impact of Scribes with Flow Coordination Duties on Throughput in an Academic Emergency Department

Introduction: With the increasing influence of electronic health records in emergency medicine came concerns of decreasing operational efficiencies. Particularly worrisome was increasing patient length of stay (LOS). Medical scribes were identified to be in a good position to quickly address barriers to treatment delivery and patient flow. The objective of this study was to investigate patient LOS in the mid- and low-acuity zones of an academic emergency department (ED) with and without medical scribes.Methods: A retrospective cohort study compared patient volume and average LOS between a cohort without scribes and a cohort after the implementation of a scribe-flow coordinator program. Patients were triaged to the mid-acuity Vertical Zone (primarily Emergency Severity Index [ESI] 3) or low-acuity Fast Track (primarily ESI 4 and 5) at a tertiary academic ED. Patients were stratified by treatment zone, acuity level, and disposition.Results: The pre-intervention and post-intervention periods included 8900 patients and 9935 patients, respectively. LOS for patients discharged from the Vertical Zone decreased by 12 minutes from 235 to 223 minutes (p<0.0001, 95% confidence interval [CI], -17,-7) despite a 10% increase in patient volume. For patients admitted from the Vertical Zone, volume increased 13% and LOS remained almost the same, increasing from 225 to 228 minutes (p=0.532, 95% CI, -6,12). For patients discharged from the Fast Track, volume increased 14% and LOS increased six minutes, from 89 to 95 minutes (p<0.0001, 95% CI, 4,9). Predictably, only 1% of Fast Track patients were admitted.Conclusion: Despite substantially increased volume, the use of scribes as patient flow facilitators in the mid-acuity zone was associated with decreased LOS. In the low-acuity zone, scribes were not shown to be as effective, perhaps because rapid patient turnover required them to focus on documentation

A Year-Long Study of Fourth Graders? Sense-Making with Modeling across Phenomena

The research question guiding this study was, How do features of models and the contexts in which they are taught and used influence upper elementary students’ sense-making and engagement in the practice of constructing and using models? An emphasis on engaging students in authentic and meaningful inquiry has led to a renewed focus on incorporating the scientific practices in science instruction. One practice central to the work of scientists is scientific modeling (Duschl, 2008; Manz, 2012). This study investigated how engaging in the practice of scientific modeling through the interpretation and construction of models influenced students’ sense-making about scientific concepts and epistemological ideas related to modeling. The study took place in one 4th grade class across an entire academic year of science instruction. The teacher enacted a project-based learning science curriculum, comprised of three units, the development of which was guided by the Next Generation Science Standards and Common Core State Standards. Each unit had a different central phenomenon (i.e., erosion, renewable energy sources, communication), but all units covered concepts related to energy and energy transfer. During each unit, students interpreted or constructed physical, paper-and-pencil, or animated computerized models. Case study and design-based research methods were used to conduct an instrumental case study of the modeling events in one classroom with 36 students. Data sources included: video and audio recordings, field notes, researcher memos, student artifacts, assessments, and interviews with focal students during each instructional unit. The case was comprised of multiple sub-cases at the levels of the class and individual students. Class sub-cases detailed the ways in which engagement in the practice of modeling influenced students’ discussions during whole-class instruction in each of the three units. Individual students’ sub-cases documented the conceptual and epistemological sense-making trajectories of focal students within and across units of instruction. Focal students were selected for each unit to reflect a range of prior knowledge – low, typical, high – using unit pre-assessment measures. The interpretation and construction of different types of models across a range of phenomena supported students and the teacher to introduce and take up ideas related to the scientific concepts in the units and epistemological aspects of modeling. Focal students demonstrated growth in their conceptual understandings related to the phenomena in each unit; however, students struggled to apply their understanding related to energy transfer in the more abstract contexts of renewable energy sources and communication. In addition, low levels of prior knowledge influenced specific students’ sense-making, suggesting that students may require a threshold of prior knowledge to engage productively in the practice of modeling. Students demonstrated a trajectory of epistemological sense-making that began by discussing the purpose of models, followed by ways to improve the communicative power of models, and then the use of data to inform model construction. Constructing models provided insight into students’ sense-making related to concepts and epistemological ideas related to modeling. The ability to include animation of student-constructed models also provided opportunities for students to show processes at work in the phenomena studied (e.g., erosion caused by moving water, electricity generation using wind and water, and the relationship between volume and distance). These findings suggest that engaging in the practice of modeling can support students’ scientific sense-making. Implications for curriculum design, instructional practice, teacher learning and professional development, and policy are considered.PHDEducation & PsychologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143957/1/merbaker_1.pd

Parent and Teacher Perceptions of Elementary School Homework

The purpose of this qualitative study was to examine the perceptions of parents and teachers of elementary school students regarding homework. Specifically, the researcher examined parent and teacher perceptions, perceptions of teachers in kindergarten through fifth grades, and parents of elementary students in kindergarten through fifth grades. In this qualitative study, the researcher analyzed feedback obtained from two focus groups: a group of three parents and a group of three teachers. One-on-one in-depth interviews of seven parents or guardians and seven elementary school teachers were utilized. These interviews were conducted in settings chosen by the participants. All participants worked in, or had children enrolled in, one school division in Southwest Virginia. All interviews were recorded, transcribed verbatim, and examined by the participants to validate accuracy before coding began. Coded analysis of interview data revealed emergent themes based on frequency of occurrence. Additionally, noteworthy data discussed by participants were documented. The findings of the study indicate that homework for elementary school students can be both beneficial and detrimental for elementary school students. The following themes emerged from analysis of participant interviews: homework can lead to stress; homework should be differentiated; homework should be brief; failing to complete homework results in school consequences; homework reveals student successes and areas of concern; homework amounts don’t increase with grade level progression; nightly reading homework is acceptable; teachers have a misconception between what they believe they are assigning and what is actually occurring; and homework must have a purpose. Moreover, noteworthy ideas were: teachers will make changes to homework based on parent feedback; homework impacts sleep; homework reduction can be beneficial; parents enjoy having homework options; parents appreciate information about homework; and teachers do not like assigning homework