The Albedo Distribution of Near Earth Asteroids

The cryogenic WISE mission in 2010 was extremely sensitive to asteroids and not biased against detecting dark objects. The albedos of 428 Near Earth Asteroids (NEAs) observed by WISE during its fully cryogenic mission can be fit quite well by a 3 parameter function that is the sum of two Rayleigh distributions. The Rayleigh distribution is zero for negative values, and follows $f(x) = x \exp[-x^2/(2\sigma^2)]/\sigma^2$ for positive x. The peak value is at x=\sigma, so the position and width are tied together. The three parameters are the fraction of the objects in the dark population, the position of the dark peak, and the position of the brighter peak. We find that 25.3% of the NEAs observed by WISE are in a very dark population peaking at $p_V = 0.03$, while the other 74.7% of the NEAs seen by WISE are in a moderately dark population peaking at $p_V = 0.168$. A consequence of this bimodal distribution is that the Congressional mandate to find 90% of all NEAs larger than 140 m diameter cannot be satisfied by surveying to H=22 mag, since a 140 m diameter asteroid at the very dark peak has H=23.7 mag, and more than 10% of NEAs are darker than p_V = 0.03.Comment: 7 pages LaTex, 4 figures, accepted for publication in the Astronomical Journa

A Multi-Scale Cell-Based Model to Simulate and Elucidate the Mechanisms Controlling Tumor-Induced Angiogenesis.

Tumor-induced angiogenesis, which is the formation of new blood vessels from existing vasculature in response to chemical signals from a tumor, is a crucial step in cancer invasion and metastasis. Although the sequential steps involved in tumor-induced angiogenesis are well known, the interplay between the biochemical and biomechanical mechanisms (e.g., cell-cell and cell-ECM interactions, and intracellular signaling pathways) that affect angiogenesis is largely unresolved. The focus of this dissertation is to develop a multi-scale model of tumor-induced angiogenesis that considers the evolving composition of the stroma and the role of cellular interactions with its major component, the extracellular matrix, in order to better understand how to manipulate these processes for therapeutic gain. Key features of this biophysical model include: (1) linking processes occurring on multiple time scales, (2) controlling processes at the level of the individual cell, (3) using physical constraints and energy minimization to capture emergent behaviors without prescribing phenomenological rules, and (4) quantifying morphological details that are not currently possible to capture with continuous models. We develop a numerical code ANGIO implementing the biophysical model and simulate tumor-induced angiogenesis. Using ANGIO, we examine and report on the following critical scientific areas: (1) the relative importance of chemotaxis and mechanical forces in cell migration, (2) how the topology of the extracellular matrix influences cell migration and vascular structure, and (3) the relationship between external stimuli and cell phenotype. These results translate and synthesize a large body of compartmentalized research on angiogenesis and are meant to inform and advance efforts to develop new approaches for treating cancer and other angiogenesis-dependent diseases.Ph.D.Applied and Interdisciplinary MathematicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/57721/2/albauer_1.pd

Associations between early exposure to intimate partner violence, parental depression and subsequent mental health outcomes

Objective: To examine the association between parent reports of intimate partner violence (IPV) and depressive symptoms within the first 3 years of a child’s life with subsequent mental health conditions and psychotropic drug treatment. Design: Prospective cohort study linking parental IPV and depression with subsequent billing and pharmacy data. Setting: 4 pediatric clinics between November 2004 and June 2012 Patients/Participants: 2,422 children Main Exposure: Any report of IPV and/or parental depressive symptoms from birth to 3 years of age. Main Outcome Measures: ICD-9 mental health diagnoses and any psychotropic drug treatment between 3 and 6 years of age. Results: 2.4% of caregivers (n=58) reported both IPV and depressive symptoms before their children were 3 years of age, 3% (n=69) of caregivers reported IPV only, 29% (n=704) reported depressive symptoms only, and 65.7% (n=1,591) reported neither exposure. Children of parents reporting both IPV and depressive symptoms were more likely to have a diagnosis of attention deficit hyperactivity disorder (ADHD) (AOR 4.0; 95% CI: 1.5-10.9), even after adjusting for child gender, race/ethnicity, and insurance type. Children whose parents reported depressive symptoms were more likely to have been prescribed psychotropic medication (AOR 1.9; 95% CI: 1.0-3.4). Conclusions: Exposure to both IPV and depression before 3 years is associated with preschool onset ADHD; and early exposure to parental depression is associated with being prescribed psychotropic medication

Agent-Based Modeling of Host-Pathogen Systems: The Successes and Challenges

Agent-based models have been employed to describe numerous processes in immunology. Simulations based on these types of models have been used to enhance our understanding of immunology and disease pathology. We review various agent-based models relevant to host-pathogen systems and discuss their contributions to our understanding of biological processes. We then point out some limitations and challenges of agent-based models and encourage efforts towards reproducibility and model validation.Comment: LaTeX, 12 pages, 1 EPS figure, uses document class REVTeX 4, and packages hyperref, xspace, graphics, amsmath, verbatim, and SIunit

Greater than the Sum of its Parts: Centering Science within Elementary STEM Education

Conceptualizing STEM Integration For our reform efforts, the fundamental question to consider was, “What is STEM learning, or what should count as STEM learning?” The different models and definitions for Integrated STEM education range from STEM disciplines traditionally taught as separate and distinct content areas to integration among the four STEM disciplines (NAE and NRC, 2014; Stohlmann et al., 2012). Teacher educators are often challenged to design STEM learning experiences within teacher preparation courses that prepare for the reality of classrooms while presenting pedagogical alternatives (Corp et al., 2020). Many researchers, for instance, Roehrig et al. (2012) distinguish between content and context integration of STEM. Content integration requires the blending of knowledge from different content fields into a single curricular activity or unit to build a collective knowledge of STEM from multiple content areas (Roehrig et al., 2012; Wang et al., 2011) while context integration, “primarily focuses on the content of one discipline and uses contexts from others” to make the content more relevant (Roehrig et al., 2012, p. 9). Most researchers conclude that STEM integration should involve the merging of some or all the STEM disciplines to solve real-world problems (Moore et al., 2020; Rinke et al., 2016). Our conceptualization of STEM integration stems from (1) Dewey’s work (1938) that highlights learning as an active process that involves students engaged in experiences situated in and connected to the real world and, (2) ideas based on social constructivism developed by Vygotsky (1978) that emphasize learning via social interactions among individuals within a social setting. Constructionist theory (Ackermann, 2001; Harel and Papert, 1991; Papert, 1980) also framed learning experiences in the integrated STEM semester. Teaching Integrated STEM calls for pedagogies that pro-mote active learning that engages students in social interactions while working collaboratively in teams (Moore et al., 2014), and knowledge that is constructed via social discourse (Stohlmann et al., 2012). Other pedagogies that are fundamental to conceptualizing STEM learning are inquiry-based and hands-on strategies promoted in the Next Generation Science Standards (Bybee, 2009); NGSS Lead States, 2013), problem-based learning that involves a problem to solve (Shaughnessy, 2013) and connections to real-life experiences (Kelley and Knowles, 2016). In leading our curriculum reform effort, we draw upon the viewpoint that STEM curriculum must involve both content and context integration. Our framework positions science at the center placing emphasis on scientific inquiry (Kelley and Knowles, 2016). Integrated STEM education has strong ties to inquiry processes allowing students to formulate questions, participate in investigations that facilitate engineering design, and integrate technology and mathematics to design solutions to complex real-world problems (Kennedy and Odell, 2014; Moore and Smith, 2014). The framework served as a guide to inform our Integrated STEM curriculum design and STEM pathways (shared assignments) across multiple courses within the STEM Semester as explained in the subsequent sections

NEOWISE-R Observation of the Coolest Known Brown Dwarf

The Wide-field Infrared Survey Explorer (WISE) spacecraft has been reactivated as NEOWISE-R to characterize and search for Near Earth Objects. The brown dwarf WISE J085510.83-071442.5 has now been reobserved by NEOWISE-R, and we confirm the results of Luhman (2014b), who found a very low effective temperature ($\approx 250$ K), a very high proper motion (8.1 +/- 0.1 arcsec/yr) , and a large parallax (454 +/- 45 mas). The large proper motion has separated the brown dwarf from the background sources that influenced the 2010 WISE data, allowing a measurement of a very red WISE color of W1-W2 $> 3.9$ mag. A re-analysis of the 2010 WISE astrometry using only the W2 band, combined with the new NEOWISE-R 2014 position, gives an improved parallax of 448 +/- 33 mas and proper motion of 8.08 +/- 0.05\; arcsec/yr. These are all consistent with Luhman (2014b).Comment: 6 pages, AJ accepte

Improving treatment and survival: a population‐based study of current outcomes after a hepatic resection in patients with metastatic colorectal cancer

AbstractBackgroundPopulation‐based studies historically report underutilization of a resection in patients with colorectal metastases to the liver. Recent data suggest limitations of the methods in the historical analysis. The present study examines trends in a hepatic resection and survival among Medicare recipients with hepatic metastases.MethodsMedicare recipients with incident colorectal cancer diagnosed between 1991 and 2009 were identified in the SEER(Surveillance, Epidemiology and End Results)‐Medicare dataset. Patients were stratified into historical (1991–2001) and current (2002–2009) cohorts. Analyses compared treatment, peri‐operative outcomes and survival.ResultsOf 31 574 patients with metastatic colorectal cancer to the liver, 14 859 were in the current cohort treated after 2002 and 16 715 comprised the historical control group. The overall proportion treated with a hepatic resection increased significantly during the study period (P< 0.001) with pre/post change from 6.5% pre‐2002 to 7.5% currently (P < 0.001). Over time, haemorrhagic and infectious complications declined (both P ≤ 0.047), but 30‐day mortality was similar (3.5% versus 3.9%, P = 0.660). After adjusting for predictors of survival, the use of a hepatic resection [hazard ratio (HR) = 0.40, 95% confidence interval (CI): 0.38–0.42, P < 0.001] and treatment after 2002 (HR = 0.88, 95% CI: 0.86–0.90, P < 0.001) were associated with a reduced risk of death.ConclusionsCase identification using International Classification of Diseases, 9th Revision (ICD‐9) codes is imperfect; however, comparison of trends over time suggests an improvement in multimodality therapy and survival in patients with colorectal metastases to the liver

Antipsychotic Prescribing Pathways, Polypharmacy, and Clozapine Use in Treatment of Schizophrenia

Objective To ensure optimal care for patients with schizophrenia, antipsychotic medications must be appropriately prescribed and used. Therefore, the primary objectives of this study were to identify and describe pathways for antipsychotic prescribing, assess the consistency of observed pathways with treatment guidelines, and describe variability across facilities. Methods Data from Veterans Affairs administrative data sets from fiscal year (FY) 2003 to FY 2007 were gathered for analysis in this retrospective cohort study of antipsychotic prescribing pathways among 13 facilities across two regional networks. Patients with a new episode of care for schizophrenia or schizoaffective disorder in FY 2005 were identified, and antipsychotic prescribing history was obtained for two years before and after the index diagnosis. Demographic characteristics and distribution of comorbidities were assessed. Median medical center rates of polypharmacy were calculated and compared with Fisher’s exact test. Results Of 1,923 patients with a new episode of schizophrenia care, 1,003 (52%) had complete data on prescribing pathways. A majority (74%) of patients were prescribed antipsychotic monotherapy, and 19% received antipsychotic polypharmacy. Of patients receiving antipsychotic polypharmacy, 65% began polypharmacy within 90 days of starting any antipsychotic treatment. There was a fourfold difference in polypharmacy across facilities. Antipsychotic polypharmacy was not associated with geographic location or medical center patient volume. Clozapine utilization was low (0%–2%). Conclusions Retrospective examination of longitudinal prescribing patterns identified multiple antipsychotic prescribing pathways. Although most patients received guideline-concordant care, antipsychotic polypharmacy was commonly used as initial treatment, and there was substantial variability among facilities. Study findings suggest the utility of secondary data to assess treatment adaptation or switching for practical clinical trials