928 research outputs found
Exploring adaptation with evolutionary activity plots
No full textEvolutionary activity statistics and their visualization are introduced, and their motivation is explained. Examples of their use are described, and their strengths and limitations are discussed. References to more extensive or general accounts of these techniques are provided
Quality indicators for blogs and podcasts used in medical education: modified Delphi consensus recommendations by an international cohort of health professions educators
No full textBackgroundQuality assurance concerns about social media platforms used for education have arisen within the medical education community. As more trainees and clinicians use resources such as blogs and podcasts for learning, we aimed to identify quality indicators for these resources. A previous study identified 151 potentially relevant quality indicators for these social media resources.ObjectiveTo identify quality markers for blogs and podcasts using an international cohort of health professions educators.MethodsA self-selected group of 44 health professions educators at the 2014 International Conference on Residency Education participated in a Social Media Summit during which a modified Delphi consensus study was conducted to determine which of the 151 quality indicators met the a priori ≥90% inclusion threshold.ResultsThirteen quality indicators classified into the domains of credibility (n=8), content (n=4) and design (n=1) met the inclusion threshold.ConclusionsThe quality indicators that were identified may serve as a foundation for further research on quality indicators of social media-based medical education resources and prompt discussion of their legitimacy as a form of educational scholarship
Hydroamination of terminal allylic imines, allylic amines, and internal and terminal homoallylic amines: Regioselective and regiodivergent transformations
Get PDFC–N bonds are ubiquitous in organic chemistry. Mild methods that allow for the direct formation of this motif from readily accessible functional groups would represent a powerful advance in organic synthesis. The intermolecular hydroamination of alkenes and amines represents a novel approach towards these disconnections from readily accessible functional groups. This transformation can streamline the synthesis of complex molecules and often allows access to two regioisomers (Markovnikov and anti-Markovnikov) from one starting material.
1,2-diamines are a common motif in many organic molecules. However, their synthesis often involves a lengthy, multi-step synthetic sequence. We report the Rh- and Ir-catalyzed addition of secondary cyclic, secondary acyclic, and primary acyclic (both aryl and aliphatic) amines to allyl amine. This transformation is highly chemoselective, regioselective, functional group tolerant, and can be used to form trans-diamines with excellent selectivity. Future directions for this method, including anti-Markovnikov and/or asymmetric hydroamination are discussed.
The anti-Markovnikov hydroamination of aliphatic alkenes is a significant challenge for organometallic chemists. These products are typically formed via formal hydroamination. We report the Rh-catalyzed anti-Markovnikov selective hydroamination of homoallylic amines to form 1,4-diamines with electron rich secondary cyclic and acyclic amine nucleophiles. This transformation is tolerant of a variety of substituents on the homoallylic amine and mechanistic studies on these substrates are summarized.
The regiodivergent functionalization of a substrate is a powerful method in organic chemistry; in the hydroamination literature, this transformation typically requires activated alkenes (allenes, dienes, etc.) and is limited in scope. The regiodivergent intermolecular hydroamination of homoallylic amines to selectively form either 1,3- or 1,4-diamines is disclosed. This method features both novel aryl amine nucleophiles and catalysts to form the desired product. This transformation is demonstrated on both terminal and internal alkenes and future directions are proposed.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2019-12-01The student, Seth Ensign, accepted the attached license on 2017-09-01 at 07:03.The student, Seth Ensign, submitted this Dissertation for approval on 2017-09-01 at 07:07.This Dissertation was approved for publication on 2017-09-14 at 13:12.DSpace SAF Submission Ingestion Package generated from Vireo submission #11629 on 2018-03-13 at 10:32:34Made available in DSpace on 2018-03-13T17:29:02Z (GMT). No. of bitstreams: 5
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Previous issue date: 2017-09-14Embargo set by: Seth Robbins for item 105429
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Global Emergency Medicine Journal Club: A Social Media Discussion About the Outpatient Management of Patients With Spontaneous Pneumothorax by Using Pigtail Catheters
Get PDFAnnals of Emergency Medicine collaborated with an educational Web site, Academic Life in Emergency Medicine (ALiEM) to host a public discussion featuring the 2014 Annals article on the outpatient management of patients with a spontaneous pneumothorax by using pigtail catheters. The objective was to curate a 14-day (November 10 to 23, 2014) worldwide academic dialogue among clinicians about the article. Four online facilitators hosted the multimodal discussion on the ALiEM Web site, Twitter, and Google Hangout. Comments across the social media platforms were curated for this report, as framed by 4 preselected questions. Engagement was tracked through Web analytic tools. Blog comments, tweets, and video expert commentary involving the featured article are summarized and reported. The dialogue resulted in 1,023 page views from 347 cities in 49 countries on the ALiEM Web site, 279,027 Twitter impressions, and 88 views of the video interview with experts. This Global Emergency Medicine Journal Club created a virtual community of practice from around the world and identified common themes around the management of spontaneous pneumothorax, which included substantial practice variation in regard to inpatient versus outpatient management, location of chest tube, the use of aspiration, and chest radiography after placement
Nanoscale infrared absorption imaging and tomography
Get PDFNear-field spectroscopic imaging techniques offer a non-perturbative, molecular contrast for characterization of nanomaterials. While several techniques now provide nanoscale chemical maps by combining molecular vibrational spectroscopies with Atomic Force Microscopy (AFM), data are often complicated by the measurement apparatus, light matter interaction scheme and the low signal to noise ratio. Together, these effects have not permitted reliable analytical measurements in a near-field configuration. In this thesis, we study the contrast mechanism of contact mode Atomic Force Microscopy – Infrared (AFM-IR) spectroscopic imaging to enable accurate, nanoscale infrared absorption imaging.
We first describe the analytical solution of a rectangular cross-section cantilever beam mechanically coupled to a vertically-perturbed surface. From this understanding, we show the AFM-IR signal (recorded using heterodyne detection) can be described as the product of the local photo-induced, sample expansion and the cantilever resonance response (responsivity). We use the insight obtained to develop a new approach for removing cantilever responsivity contrast by recording an additional signal resulting from a constant reference expansion generated by a mechanical actuator (piezo) placed under the sample. Dividing the raw AFM-IR contrast by this reference signal at each sample position eliminates spatial responsivity variations enabling accurate chemical imaging.
Although the ratio approach corrects for spatial responsivity variations, time-dependent changes in responsivity produce noise which scales with cantilever deflection. Next, we demonstrate a closed-loop controller for the piezo actuator to maintain zero deflection through destructive interference of the piezo and photo-induced expansions. Measuring the piezo voltage offers an alternative AFM-IR measurement with low susceptibility to both spatial and temporal changes in responsivity improving the SNR by >5x.
Last, we describe an analytical Green’s function derived from Thermoelasticity relating 3 dimensional heat generation to vertical surface expansion for a n-layer laminated, half-space. From this theory, we show the image resolution is dependent on parameters such as sample thickness and material properties and propose a new method for distinguishing absorption in 3 dimensions harnessing the frequency dependent thermal diffusion.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2022-05-01The student, Seth Kenkel, accepted the attached license on 2020-04-25 at 15:25.The student, Seth Kenkel, submitted this Dissertation for approval on 2020-04-25 at 15:36.This Dissertation was approved for publication on 2020-05-07 at 13:24.DSpace SAF Submission Ingestion Package generated from Vireo submission #15073 on 2020-08-25 at 17:40:56Made available in DSpace on 2020-08-27T00:50:02Z (GMT). No. of bitstreams: 2
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Leveraging Tweets, Citations, and Social Networks to Improve Bibliometrics
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Global Emergency Medicine Journal Club: A Social Media Discussion About the Outpatient Management of Patients With Spontaneous Pneumothorax by Using Pigtail Catheters
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