141 research outputs found
Publisher Correction: Emergence of Fermi arcs due to magnetic splitting in an antiferromagnet
No full textThis Publisher Correction is published as Schrunk, Benjamin, Yevhen Kushnirenko, Brinda Kuthanazhi, Junyeong Ahn, Lin-Lin Wang, Evan O’Leary, Kyungchan Lee et al. "Publisher Correction: Emergence of Fermi arcs due to magnetic splitting in an antiferromagnet." Nature 605, no. 7909 (2022): E5-E5.
DOI: 10.1038/s41586-022-04705-1.
Copyright 2022 The Author(s).
Posted with permission
Hot playgrounds and children's health: a multiscale analysis of surface temperatures in Arizona, USA
No full textabstract: Objectives: To provide novel quantification and advanced measurements of surface temperatures (Ts) in playgrounds, employing multiple scales of data, and provide insight into hot-hazard mitigation techniques and designs for improved environmental and public health. Methods: We conduct an analysis of Ts in two Metro-Phoenix playgrounds at three scales: neighborhood (1 km resolution), microscale (6.8 m resolution), and touch-scale (1 cm resolution). Data were derived from two sources: airborne remote sensing (neighborhood and microscale) and in situ (playground site) infrared Ts (touch-scale). Metrics of surface-to-air temperature deltas (Ts–a) and scale offsets (errors) are introduced. Results: Select in situ Ts in direct sunlight are shown to approach or surpass values likely to result in burns to children at touch-scales much finer than Ts resolved by airborne remote sensing. Scale offsets based on neighbourhood and microscale ground observations are 3.8 ◦C and 7.3 ◦C less than the Ts–a at the 1 cm touch-scale, respectively, and 6.6 ◦C and 10.1 ◦C lower than touch-scale playground equipment Ts, respectively. Hence, the coarser scales underestimate high Ts within playgrounds. Both natural (tree) and artificial (shade sail) shade types are associated with significant reductions in Ts. Conclusions: A scale mismatch exists based on differing methods of urban Ts measurement. The sub-meter touch-scale is the spatial scale at which data must be collected and policies of urban landscape design and health must be executed in order to mitigate high Ts in high-contact environments such as playgrounds. Shade implementation is the most promising mitigation technique to reduce child burns, increase park usability, and mitigate urban heating.Corresponding Author:
Jennifer K. Vanos
Texas Tech University
[email protected]
Inner Shelf Sorted Bedforms: Long-Term Evolution and a New Hybrid Model
No full textSorted bedforms are spatial extensive (100 m-km) features present on many inner continental shelves with subtle bathymetric relief (cm-m) and localized, abrupt variations in grain size (fine sand to coarse sand/gravel). Sorted bedforms provide nursery habitat for fish, are a control on benthic biodiversity, function as sediment reservoirs, and influence nearshore waves and currents. Research suggests these bedforms are a consequence of a sediment sorting feedback as opposed to the more common flow-bathymetry interaction. This dissertation addresses three topics related to sorted bedforms: 1) Modeling the long-term evolution of bedform patterns, 2) Refinement of morphological and sediment transport relations used in the sorted bedform model with `machine learning'; 3) Development of a new sorted bedform model using these new `data-driven' components. Chapter 1 focuses on modeling the long term evolution of sorted bedforms. A range of sorted bedform model behaviors is possible in the long term, from pattern persistence to spatial-temporal intermittency. Vertical sorting (a result of pattern maturation processes) causes the burial of coarse material until a critical state of seabed coarseness is reached. This critical state causes a local cessation of the sorting feedback, leading to a self-organized spatially intermittent pattern, a hallmark of observed sorted bedforms. Various patterns emerge when numerical experiments include erosion, deposition, and storm events. Modeling of sorted bedforms relies on the parameterization of processes that lack deterministic descriptions. When large datasets exist, machine learning (optimization tools from computer science) can be used to develop parameterizations directly from data. Using genetic programming (a machine learning technique) and large multisetting datasets I develop smooth, physically meaningful predictors for ripple morphology (wavelength, height, and steepness; Chapter 2) and near bed suspended sediment reference concentration under unbroken waves (Chapter 3). The new predictors perform better than existing empirical formulations. In Chapter 3, the new components derived from machine learning are integrated into the sorted bedform model to create a `hybrid' model: a novel way to incorporate observational data into a numerical model. Results suggest that the new hybrid model is able to capture dynamics absent from previous models, specifically, the two observed end-member pattern modes of sorted bedforms (i.e., coarse material on updrift bedform flanks or coarse material in bedform troughs). However, caveats exist when data driven components do not have parity with traditional theoretical components of morphodynamic models, and I address the challenges of integrating these disparate pieces and the future of this type of `hybrid' modeling.</p
In-Depth Analysis and Program Notes on a Selection of Wind Band Music
No full textThis document is an in-depth analysis of five pieces composed for wind band: Cloudburst by Eric Whitacre, Promenade and Galop by Daniel Kallman, Ave Maria by Franz Biebl (arranged by Robert Cameron), A Hymn for the Lost and the Living by Eric Ewazen, and Five English Folk Songs by Ralph Vaughan Williams (arranged by Evan Feldman). These works were conducted by the author with the Minnesota State University, Mankato Concert Wind Ensemble between October 2010 and January 2012. The following pages contain biographical information on each composer (and arranger where applicable), program notes, formal analysis, and conducting and rehearsal considerations by the author. In addition, each analysis concludes with a personal reflection in which the author describes how each piece helped in his development as a conductor from baton technique to personal growth
Evidence for the influence of irrigation on precipitation intensity and totals in the midwestern United States: observational and modeling perspectives
No full textSignificant increases in summer precipitation occurred in the Midwestern United States over the last century for reasons that remain unclear. It is postulated that the expansion of irrigation and cropland in the central US over the past sixty years has been a major contributor to these observed increases in precipitation. As a first step toward attribution of these regional precipitation changes, a detailed analysis of observed daily summer precipitation frequency and intensity is conducted for the contiguous United States over multiple spatial scales and time periods from 1895 to 2011. Robust increases in precipitation frequency, total precipitation, and moderate to heavy precipitation intensity are identified during July and August in the Midwestern US. Analysis of changes in mean monthly precipitation from the early- to late-20th century initially points to increasing frequency as the source of increasing monthly precipitation in the Midwestern US during the summer, especially during August; however, comparable increases in precipitation frequency occur during other times of the year. On the other hand, changes in precipitation intensity and total precipitation are both greatest during July and August and coincide spatially in the Midwestern US. Additionally, the greatest intensity change occurs downwind of the most heavily irrigated regions, especially for the period between 1950 and 1980 when irrigation rapidly intensified. A 15-day simulation using the WRF regional climate model with a simplified irrigation scheme over Nebraska confirmed the postulated increase in moisture, decrease in temperature, and subsequent increases in both convective inhibition and convective available potential energy over Nebraska, which led to weakened convection over the irrigated areas. Wind anomalies produced by irrigation seem to be instrumental in enhancing precipitation intensity and totals downwind of Nebraska in general, and in the eastern Midwest region for one particular heavy precipitation event. The increases in Midwestern precipitation in both analyses – one based on observation and rooted in reality and one based on model experiments and controlled for irrigation – support the hypothesis that irrigation in Nebraska has led to an increase in the intensity and total of precipitation downwind of the irrigated regions.Ph.D.Includes bibliographical referencesby Ross Evan Alte
Essays In Labor Economics
No full textThe three essays of this dissertation are studies of individual choice and outcomes in labor-economics related problems. In the first chapter, I use an individual's rank in his coworker-comparison group to predict whether he leaves his job and the amount of earnings growth he will experience over his next few years. Even after controlling for a variety of individual and firm observables and unobservables, I find that an individual's rank is positively correlated with his earnings growth on the current job but negatively correlated with his earnings growth when he changes jobs. The mean reversion of job changers' earnings with respect to rank suggests that rank is a signal of an individual's match productivity with his current firm. In the second chapter, my co-author and I use a flexible decomposition procedure for job-matching to distinguish changes in job-to-job flows due to structural factors of the labor market from changes due to the evolving composition of workers and firms. We find that the likelihood of workers moving to firms 25-100 miles away from their current firm when changing jobs has increased. This increased integration of local labor markets has gone undetected by other studies of mobility, which focus on interstate and even inter-county job and residential migration. In the third chapter, I study whether US citizens have become more or less likely over time to marry someone with whom they share a state of birth. Using a variety of descriptive statistics, I find that the proportion of marriages between citizens with different states of birth has increased. Individuals born in later years and those having higher education are generally more likely to marry someone born in a different state
Opportunities and challenges for personal heat exposure research
No full textabstract: Background:
Environmental heat exposure is a public health concern. The impacts of environmental heat on mortality and morbidity at the population scale are well documented, but little is known about specific exposures that individuals experience.
Objectives:
The first objective of this work was to catalyze discussion of the role of personal heat exposure information in research and risk assessment. The second objective was to provide guidance regarding the operationalization of personal heat exposure research methods.
Discussion:
We define personal heat exposure as realized contact between a person and an indoor or outdoor environment that poses a risk of increases in body core temperature and/or perceived discomfort. Personal heat exposure can be measured directly with wearable monitors or estimated indirectly through the combination of time–activity and meteorological data sets. Complementary information to understand individual-scale drivers of behavior, susceptibility, and health and comfort outcomes can be collected from additional monitors, surveys, interviews, ethnographic approaches, and additional social and health data sets. Personal exposure research can help reveal the extent of exposure misclassification that occurs when individual exposure to heat is estimated using ambient temperature measured at fixed sites and can provide insights for epidemiological risk assessment concerning extreme heat.
Conclusions:
Personal heat exposure research provides more valid and precise insights into how often people encounter heat conditions and when, where, to whom, and why these encounters occur. Published literature on personal heat exposure is limited to date, but existing studies point to opportunities to inform public health practice regarding extreme heat, particularly where fine-scale precision is needed to reduce health consequences of heat exposure.Corresponding Author:
David Hondula
Arizona State University
[email protected]
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Scans, Residues, Misrecognitions and Other Materialities of Loss
No full textShifting economic and political conditions in many urban areas have resulted in queer spaces disappearing at an increasing rate. These bars, clubs, bookstores and other architectural environments occupied by various members of the LGBTQ2SIA+ community are central to a history of sexuality. Their subsequent absence signals a potential erasure of significant aspects of personal and collective memory. As a response to this slow loss, Berlin-based artist and architect Author 2 has employed architectural scanning technology to create highly detailed, digital models of various edifices, interiors, public spaces and monuments in the German city. The three-dimensional models are then processed as key components of two parallel projects: a website that enables visitors to explore a selection of spaces paired with recorded interviews and a virtual reality (VR) artwork animating the architectural archive. In this conversation, Busch discusses the ongoing project Scanning the Horizon alongside the application LiDAR laser scanning techniques to create highly accurate visualizations of various built structures throughout Berlin and convey distinctly queer experiences of space. The artist defines how publicity, existing access and other protocols shape the selection of spaces featured in the project. Queer tactics of cruising architecture via the equipment are further expanded to address the theoretical potential of the limitations of the technology and the aesthetic experience of the website and VR work. In this regard, the growing archive is examined as a repository or remainder of space that simultaneously embraces and counters the ephemerality of LGBTQ2SIA+ records
Interplay Between Proteins, Lipids, and Membrane Architecture in Dynamic Structure and Allosteric Regulation of Membrane Proteins
No full textThe plasma membrane of living cells forms the ultimate barrier sequestering cellular function from the surroundings. The membrane itself contains both integral and peripheral membrane proteins and is segregated into ordered and disordered microdomains. In this regime, lipids regulate the function of membrane proteins. Likewise, the presence of membrane proteins incurs an effect on the properties of the bilayer. Thus, there is a critical physiological role for the functional interplay between the membrane and its protein species in homeostatic modulation of lipid bilayer functionality. In this dissertation, I use combined functional assays, molecular dynamics (MD) simulations, and solid-state nuclear magnetic resonance (SSNMR) to unravel the functional interplay between lipid regulation of membrane proteins and formation of membrane architecture. To achieve this goal, I first implemented a version of codon harmonization dubbed Dna codon Usage for Measured Base (DUMB) optimization which was applied to a chimeric G protein-gated Inward Rectifying K+ (GIRK) channel as a proof of concept. Codon harmonization aims to reintroduced more deoptimized codons into the heterologous sequence to match the native codon usage pattern under the hypothesis that more native-like site specific translational rates aid in proper cotranslational folding and therefore higher quality and quantity of protein yield. It was found that DUMB optimization increased yield from ~ 8 to ~14 mg/L. This technique was then applied to the C-C motif Chemokine Receptor 3 (CCR3). CCR3 is a class A G protein-coupled receptor (GPCR) expressed by immune cells. Interaction with peptide agonist chemokines triggers a CCR3-mediated signaling cascade culminating in chemotaxis of the expressing cell along the chemokine gradient. Structurally, little was known of the details of CCR3 function. Using DUMB optimization, yields of up to 4 mg CCR3 per L are observed. Building upon this, a novel fluorescence polarization assay was developed and used to show that cholesterol increases CCR3 affinity for the endogenous ligand C-C motif chemokine 11 (CCL11). Using a GTP hydrolysis assay, it was shown that this directly translated to increased G protein coupling and activation of the Gα inhibitory subunit 3 (Gαi3). Using coarse grain MD (CGMD) and PyLipID analysis, we then predicted cholesterol binding sites in CCR3. SSNMR was then used to investigate bilayer ordering and microdomain formation in membrane extracts of Burkholderia thailandensis. With NMR-level yields, uniformly 15N-13C-labeled CCR3 samples in the presence and absence of cholesterol were generated. It was observed in 2-dimensional Dipolar Assisted Rotational Resonance (2D-DARR) NMR experiments that CCR3 dynamic timescales were slowed when cholesterol was introduced to the membrane environment. Using Comparative, Objective Measurement of Protein Architectures by Scoring Shifts (COMPASS), atomistic MD simulations model structures were graded compared to experimental, unassigned chemical shifts derived from these 2D-DARR experiments. It was found that cholesterol biased regions of the receptor to specific, conserved conformations, including remodeling of the orthosteric pocket and activation pathway contacts. A suite of dynamics experiments were performed on CCR3 to identify the most efficient temperatures at which spectra can be acquired for resonance assignment purposes. Based on results, a set temperature of -40 was identified, which was related to the phase change temperature imparted by the cholesterol-containing bilayer. The findings in this dissertation provide evidence for functional interplay between lipid regulation of membrane proteins and formation of membrane architecture in the context of multiple, highly complex prokaryotic and eukaryotic systems.Embargo status: Restricted until 06/2028. To request the author grant access, click on the PDF link
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