Independent contractor

Chicago, IL, United States

Independent contractor

Chicago, IL, United States
Time filter
Source Type

van der Sanden J.J.,Canada Center For Remote Sensing | Geldsetzer T.,Independent Contractor
Canadian Journal of Remote Sensing | Year: 2015

Abstract. Canada's RADARSAT Constellation Mission (RCM) will have the capacity to acquire C-band compact polarimetry (CP) data in all imaging modes over swaths up to 500 km wide. Our study aimed to assess and develop the utility of RCM CP data for the purpose of lake ice breakup monitoring. The breaking ice and open water information content of RADARSAT-2 (R2) polarimetric data and simulated RCM CP data was compared. Despite relative losses in terms of polarization diversity and radiometric sensitivity, RCM-type CP data were concluded to make a good source of information in support lake ice breakup monitoring. For that reason, a CP-based approach, called CP_LakeIceBC, to classify breaking ice and open water for the purpose of lake ice breakup monitoring was developed. CP_LakeIceBC is driven by incidence angle information, uses five CP backscatter variables (RH, RR, RV/RH, RR/RL, and conformity), and is compatible with high- and medium-resolution RCM-type CP products. Application of CP_LakeIceBC to representative simulated products yielded classification accuracies ranging from 73.2 to 99.1% and 60.8 to 99.5% for breaking ice and open water, respectively. Résumé. La mission de la Constellation RADARSAT (MCR) du Canada aura la capacité d’acquérir des données en polarimétrie compacte (CP) en bande C dans tous les modes d’imagerie, sur des fauchées allant jusqu’à 500 km de large. Notre étude visait à évaluer et développer l’utilité des données en CP de la MCR à des fins de surveillance des débâcles lacustres. Le contenu de l’information sur l’eau libre et la rupture des glaces a été comparé à partir de données polarimétriques de RADARSAT-2 (R2) et des données en CP de la MCR. Malgré les pertes relatives en termes de la diversité de la polarisation et de la sensibilité radiométrique, il a été conclu que les données en CP de type MCR sont une bonne source d’information de soutien pour la surveillance des débâcles lacustres. Pour cette raison, une approche fondée sur la CP, nommée CP_LakeIceBC, a été développée afin de classifier la rupture de la glace et l’eau libre à des fins de surveillance de la débâcle lacustre. CP_LakeIceBC est déterminée par l’information sur l’angle d’incidence, elle utilise cinq variables CP de rétrodiffusion (RH, RR, RV/RH, RR/RL et conformité), et elle est compatible avec les produits de CP de type MCR à haute et à moyenne résolution. L’application de CP_LakeIceBC aux produits simulés représentatifs a donné des précisions de classification pour la rupture de la glace et l’eau libre allant de 73,2 % à 99,1 % et de 60,8 % à 99,5 %, respectivement. Copyright © 2015 Crown Copyright.

Smith J.N.,Purdue University | Keil A.D.,Independent Contractor | Noll R.J.,Purdue University | Cooks R.G.,Purdue University
Analyst | Year: 2011

Gaseous ammonia, a common toxic industrial compound, is not detected readily in ion trap mass spectrometers because its molecular ion falls below the low-mass cutoff (∼m/z 40) normally used when examining organic compounds. Instead, reactions of ammonia with halobenzene radical cations were used with internal electron ionization in two cylindrical ion trap miniature mass spectrometers to create a characteristic product ion by which to identify and quantify ammonia. Ammonia showed a linear response over the concentration range studied (parts per million [ppm] to parts per billion [ppb]) with limits of detection of 17 ppm and 220 ppb for experiments involving direct introduction and thermal desorption after pre-concentration, respectively. These values are comparable to ammonia's permissible exposure limit (50 ppm) and odor threshold (5 ppm). Receiver operating characteristic (ROC) curves were used to describe the method sensitivity, the probability of true positives, and the false positive rate for ammonia. A customized reaction scan function was created to select the species available for the ion/molecule reaction and set the amount of time the product ion could be accumulated in the trap. Product ion identity was verified using tandem mass spectrometry. Similar reactions with methylamine, ethylamine and the two nitriles, acetonitrile and benzonitrile, were explored. © The Royal Society of Chemistry.

Herencia J.E.,University of Bristol | Haftka R.T.,University of Florida | Balabanov V.,Independent Contractor
Structural and Multidisciplinary Optimization | Year: 2013

This paper investigates the weight penalty of a composite structure under strength and buckling constraints when cross-sections are designed from a limited number of laminates. The problem is investigated for the well known ten-bar truss structure. Results show that decreasing the number of cross-sections from nine to four has a small impact on the weight of the structure of approximately 5.4%. Furthermore, as the number of cross-sections increases, so does the number of critical constraints. This indicates higher probability of failure. © 2012 Springer-Verlag.

Barshop K.,University of Chicago | Staller K.,Massachusetts General Hospital | Semler J.,Independent Contractor | Kuo B.,Massachusetts General Hospital
Neurogastroenterology and Motility | Year: 2015

Background: Studies of symptomatic gastroparetics consistently find poor correlation with gastric emptying. We hypothesized that concomitant small bowel dysmotility may play a role in symptom causation in gastroparesis and sought to test this hypothesis by using wireless motility capsule (WMC) testing to simultaneously measure antral and duodenal area under pressure curve (AUC) in patients with delayed gastric emptying. Methods: Using a cohort from a multicenter clinical trial and a separate tertiary clinical database, we identified gastroparetics that underwent concurrent WMC testing and completed the Gastroparesis Cardinal Symptom Index, a validated questionnaire. Our study included 35 gastroparetics defined by a gastric emptying time (GET) ≥5 h. Antral and duodenal AUC were assessed at 1-h windows pre-GET and post-GET, respectively. Key Results: We found moderate correlations between duodenal AUC and symptom severity in the combined cohort (n = 35; R = -0.42; p = 0.01; 95% CI -0.7, -0.1). Removing patients with colonic delay resulted in a stronger correlation of duodenal AUC to symptom severity (n = 21; R = -0.63; p < 0.01; 95% CI -0.81, -0.31). The multicenter trial (n = 20) and clinical practice cohorts (n = 15) had significantly different symptom severity and exclusion criteria. When analyzed separately, significant correlations between duodenal AUC and symptom severity were observed (R = -0.71; p < 0.01; 95% CI -0.9, -0.4 and R = -0.72; p < 0.01; 95% CI -0.9, -0.3, respectively). Symptom severity and antral motility showed no correlation. Conclusions & Inferences: We found significant correlations between duodenal AUC and symptom severity in two cohorts of gastroparetics. Small bowel motility may contribute to symptom generation in gastroparetic patients and this may inform therapeutic considerations. Wireless motility capsule testing was used to simultaneously assess gastric and duodenal contractile motility in gastroparesis patients. Gastroparesis symptom severity was assessed using a validated questionnaire. Duodenal-rather than gastric-contractile motility correlated with symptom severity in Gastroparesis patients in two independent cohorts. © 2014 John Wiley & Sons Ltd.

Lynch E.B.,Northwestern University | Lynch E.B.,Rush University Medical Center | Holmes S.,Northwestern University | Keim K.,Rush University Medical Center | Koneman S.A.,Independent contractor
Journal of Nutrition Education and Behavior | Year: 2012

Objective: Describe beliefs about what makes foods healthful among low-income African American women. Methods: In one-on-one interviews, 28 low-income African American mothers viewed 30 pairs of familiar foods and explained which food in the pair was more healthful and why. Responses were grouped into codes describing concepts of food healthfulness. Results: Nutrient content, physical effects of food, and food categories were used to judge the healthfulness of foods. Fruits, vegetables, and dairy foods were considered the most healthful and starchy foods the least healthful because they were believed to cause weight gain. Beliefs about which foods contain which nutrients and which foods have particular physical effects varied widely across participants. Conclusions and Implications: Participants demonstrated awareness of which foods are healthful but lacked understanding of why those foods are more healthful than others. Knowledge about the health effects of foods may be necessary to motivate individuals to choose healthful foods. © 2012 Society for Nutrition Education and Behavior.

Rehfeldt G.E.,U.S. Department of Agriculture | Leites L.P.,Pennsylvania State University | Bradley St Clair J.,U.S. Department of Agriculture | Jaquish B.C.,British Columbia Ministry of forests | And 3 more authors.
Forest Ecology and Management | Year: 2014

Height growth data were assembled from 10 Pinus ponderosa and 17 Pseudotsuga menziesii provenance tests. Data from the disparate studies were scaled according to climate similarities of the provenances to provide single datasets for 781 P. ponderosa and 1193 P. menziesii populations. Mixed effects models were used for two sub-specific varieties of each species to describe clines in growth potential associated with provenance climate while accounting for study effects not eliminated by scaling. Variables related to winter temperatures controlled genetic variation within the varieties of both species. Clines were converted to climatypes by classifying genetic variation, using variation within provenances in relation to the slope of the cline to determine climatype breadth. Climatypes were broader in varieties of P. ponderosa than in P. menziesii and were broader for varieties inhabiting coastal regions of both species than for varieties from interior regions. Projected impacts of climate change on adaptedness used output from an ensemble of 17 general circulation models. Impacts were dependent on cline steepness and climatype breadth but implied that maintaining adaptedness of populations to future climates will require a redistribution of genotypes across forested landscapes. © 2014.

Rehfeldt G.E.,U.S. Department of Agriculture | Jaquish B.C.,British Columbia Ministry of forests | Saenz-Romero C.,Universidad Michoacana de San Nicolás de Hidalgo | Joyce D.G.,Independent Contractor | And 3 more authors.
Forest Ecology and Management | Year: 2014

Impacts of climate change on the climatic niche of the sub-specific varieties of Pinus ponderosa and Pseudotsuga menziesii and on the adaptedness of their populations are considered from the viewpoint of reforestation. In using climate projections from an ensemble of 17 general circulation models targeting the decade surrounding 2060, our analyses suggest that a portion of the lands occupied today primarily by coastal varieties of each species contain genotypes that should remain suitable for the future climate. A much larger portion, particularly for varieties occupying inland sites, should require either introduction of better suited species or conversion to better adapted genotypes. Regeneration strategies are considered with the goal of matching growth potential of contemporary populations to the future climate where that potential can be realized. For some lands, natural reproduction should be suitable, but most lands will require forest renewal to maintain forest health, growth, and productivity. Projected impacts also illustrate the urgent need for conservation programs for P. menziesii in Mexico. © 2014.

Hulse G.,Independent Contractor
IEEE International Conference on Electro Information Technology | Year: 2012

A method of transforming a two dimensional input image into a one dimensional time sequenced serial string at the speed of light is described. The image is transformed into serial information by varying the optical path length (OPL) relative to the position of the images pixel in space. The light traverses each pixel and enters an optical system which has varying OPL associated with each pixel. The OPL associated with each pixel will be modified with respect to every other pixel based on position. This modification allows a transformation into a timed sequence of pulses. This paper gives the computations for the various OPLs needed. It starts with a one dimensional system then expands to a two dimensional system. © 2012 IEEE.

Szanton S.L.,Johns Hopkins University | Wenzel J.,Johns Hopkins University | Connolly A.B.,Independent Contractor | Piferi R.L.,Johns Hopkins University
BMC Complementary and Alternative Medicine | Year: 2011

Background: Mindfulness-based stress reduction (MBSR) programs are becoming increasingly common, but have not been studied in low income minority older populations. We sought to understand which parts of MBSR were most important to practicing MBSR members of this population, and to understand whether they apply their training to daily challenges.Methods: We conducted three focus groups with 13 current members of an MBSR program. Participants were African American women over the age of 60 in a low-income housing residence. We tape recorded each session and subsequently used inductive content analysis to identify primary themes.Results and discussion: Analysis of the focus group responses revealed three primary themes stress management, applying mindfulness, and the social support of the group meditation. The stressors they cited using MBSR with included growing older with physical pain, medical tests, financial strain, and having grandchildren with significant mental, physical, financial or legal hardships. We found that participants particularly used their MBSR training for coping with medical procedures, and managing both depression and anger.Conclusion: A reflective stationary intervention delivered in-residence could be an ideal mechanism to decrease stress in low-income older adult's lives and improve their health. © 2011 Szanton et al; licensee BioMed Central Ltd.

Kozma C.M.,A K associates | Slaton T.,Independent Contractor | Paris A.,Vigilytics | Edgell E.T.,DePuy
Journal of Medical Economics | Year: 2013

Objective: Describe resource utilization and costs for total hip replacement (THR) and total knee replacement (TKR) for the 90 days before hospitalization for surgery, the hospital event, and the 90 and 360 days after hospitalization for surgery with emphasis on 90 days after hospitalization. Methods: A large insurance database was used to identify outpatient and summarized hospital resource use and payments (insurer perspective) for THR and TKR. A second large US database provided hospital details (charge description master level) of inpatient services, costs, and charges (hospital perspective) for a different sample of THR and TKR patients. Included patients were ≥45 years old, had no hospitalization record within 1 year before surgery, and THR length of stay (LOS) of 2-8 days or TKR LOS 2-6 days. Results: There were 22 618 THR and 50 686 TKR patients in the insurance database and 81 635 THR and 158 990 TKR in the hospital database. Average age was ∼66 years for THR and TKR patients. Median LOS was 4 days (both surgeries). Hospital costs (hospital perspective) were $17 588 in US dollars (USD) and $16 267 (USD) for THR and TKR, respectively. Reimbursement for hospital services (insurer perspective) were $22 967 (USD) and $21 583 (USD) for THR and TKR, respectively. In 90 days post-surgery, THR and TKR total payments were $3827 (USD) and $4237 (USD), respectively. Payments for the first 90 days post-surgery were 57.5% of the 360-day post-period for THR-related payments and 59.9% for TKR-related payments. Conclusion: Payers considering use of episode-of-care payment models for THR and TKR may wish to concentrate efforts on the 90 days post-discharge. Limitations: While this study used large samples of subjects, generalisability of the results may be limited since the samples were not randomized samples of THR and TKR patients. It is noteworthy that patients in the hospital sample are not the same as those in the insurer sample. Selection of hip-related and knee-related procedures and associated costs was based on qualitative review. Payers may use different billing codes or aggregate costs differently. © 2013 All rights reserved.

Loading Independent contractor collaborators
Loading Independent contractor collaborators