Photo-sensitive "flip-flop" characteristics of the developing Narcissus plant (daffodil phototropism).

MAIN CONCLUSION: The developing Narcissus pseudonarcissus plant (daffodil) is shown to face towards a preferential direction (east, south, west, or north, in that order) before flowering. Said directionality is accomplished by stem bending, a phototropic response mechanism, which is sensitive to partial blocking of the available sunlight from the local environmental. Polar distribution diagrams show that with partial environmental shading from the north, east, south, or west, the developing daffodil plant always excludes facing in that direction, to absorb maximum available sunlight. Stem buckling experiments, equivalent to stem bending, are presented measuring the Euler buckling exponent n = - 2.1 for daffodil flower stems, in good agreement with theory, r = 0.99. Individual flower stems are capable of generating 2-3 lbf of vertical force, which explains the plants ability to penetrate frozen ground cover. Results from 193 daffodil flower stems are presented, showing that 61.7% face East [95% CI 54-70%], 17.1% face South, 15.0% face West, and only 6.2% face North [95% CI 2-10%], depending strongly on the partial shading effect of the surrounding environment.

Delayed diagnosis of splenic injuries: A case series.

INTRODUCTION: Injury of the spleen may result in significant morbidity and mortality, often related to blood loss. Splenic injuries may be missed on the initial Emergency Department (ED) presentation. This study was undertaken to describe cases of delayed diagnosis, and to identify factors associated with delayed diagnosis, treatment, and outcomes. METHODS: This retrospective study examined eligible participants with injury to the spleen who were admitted between July 2015-December 2017. Eligible participants included patients age 16 and over with injury to the spleen, with two or more ED presentations prior to admission and inpatient management. Data collected included age, gender, ethnicity, trauma triage category, vital signs, mechanism of injury, CT diagnosis, time from injury to diagnosis, toxicologic test results, inpatient management, outcome, and days of hospitalization. RESULTS: Among 210 patients with splenic injury, the mean age was 36. Most participants were male (N = 132; 63%) and White (N = 165; 79%). A small percentage (6%) was not diagnosed with splenic injury during the initial ED encounter. Missed diagnosis on the initial ED visit was not associated with age, gender, ethnicity, mechanism of injury, vital signs, grade of injury, intervention, or days of hospitalization. Most patients were discharged home (N = 9); a minority died (N = 1) or were discharged to a rehabilitation facility (N = 1). CONCLUSIONS: In this study, 6% of patients with splenic injury were not diagnosed during the initial ED encounter. These patients with delayed diagnosis had similar grade of injury, need for intervention, days of hospitalization, and outcome.

Advanced myopia, prevalence and incidence analysis.

PURPOSE: Various high-percentage high-incidence medical conditions, acute or chronic, start at a particular age of onset t1 (years), accumulate or progress rapidly, with a system time constant t0 (years), typically from 1 week to 5 years, and then level off at a plateau level [Formula: see text], ultimately affecting 10-95% of the population. This report investigates the prevalence and incidence functions for myopia and high myopia as a function of age. METHODS: Fundamental prevalence versus time and incidence versus time results allow continuous prediction of myopia and high myopia population fractions as a function of age. This is a retrospective study. Nine reports are calculated with N = 444,600 subjects. There were no interventions other than usual regular eye examinations and subsequent indicated refraction change. RESULTS: The main result is continuous prediction of myopia prevalence-time data along with incidence rate data (%/year), age of onset (years), system plateau level, and system time constant (years). These parameters apply to progressive myopia and high myopia (R < -6 D), useful over several decades. CONCLUSIONS: The primary finding of this research is that the prevalence ratio of high myopes (R < -6.0 D) to common myopes is expected to increase from 15% entering college to 45% or more after college and graduate school. These statistics are particularly relevant to the many years of study required by M.D., Ph.D., and M.D./Ph.D. programs.

Mathematical Models of College Myopia.

Experimental design phase of a pilot study at Annapolis is described, using reading glasses, +1.5 D. to +3.0 D. to alleviate college myopia. College students often become 1.0 to 2.0 diopters more myopic, so reading glasses were explored to partially cancel the effects of the study environment. N = 25 different sets of (+)Add lenses are evaluated, for required adjustment period and reading comfort. Three computer models are developed to predict refraction versus time. Basic control system equations predict exponential myopia shift of refractive state R(t) with time constant t0 = 100 days. Linear, exponential and Gompertz computer results are compared calculating refraction R(t) during the college years, showing correlation coefficients |r| = 0.96 to 0.97, accurate +/-0.31 D. over a 14 year interval. Typical college myopia rate is -0.3 to -0.4 D/yr. Reading glasses may be a simple, practical solution to stabilize college myopia.

Refraction data survey: 2nd generation correlation of myopia.

The objective herein is to provide refraction data, myopia progression rate, prevalence, and 1st and 2nd generation correlations, relevant to whether myopia is random or inherited. First- and second-generation ocular refraction data are assembled from N = 34 families, average of 2.8 children per family. From this group, data are available from N = 165 subjects. Inter-generation regressions are performed on all the data sets, including correlation coefficient r, and myopia prevalence [%]. Prevalence of myopia is [M] = 38.5 %. Prevalence of high myopes with |R| >6 D is [M-] = 20.5 %. Average refraction is  = -1.84 D ± 3.22 (N = 165). For the high myopes, |R| >6 D, prevalence for the parents is [M-] = 25 %, for the 2nd generation [M-] = 16.5 %. Average myopia level for the high myopes, both generations, is  = -7.52 D ± 1.31 D (N = 33). Regression parameters are calculated for all the data sets, yielding correlation coefficients in the range r = 0.48-0.72 for some groups of myopes and high myopes, fathers to daughters, and mothers to sons. Also of interest, some categories show essentially no correlation, -0.20 < r < 0.20, indicating that the refractive errors occur randomly. Time series results show myopia diopter rates = -0.50 D/year.

Medical education in an electronic health record-mediated world.

This paper reflects on the extent to which we are preparing learners for practice in an electronic health record (EHR)-mediated world. We are currently training the last generation to remember a world without the Internet and the first who will practice in a largely EHR-mediated practice environment. We undertook a thematic review of the literature connecting medical education with e-health using the concepts of 'electronic health record' or 'electronic medical record' as a proxy for the broader notion of e-health. Our findings are more equivocal and cautious than earlier commentators might have expected and while there are examples of good practice and successful integration, the majority of articles we reviewed raised issues and problems with the current links between EHRs and medical education. Medical professionals in particular are quite ambivalent about many of the changes brought about by EHRs, and in the absence of changes in perception and practice it is likely that the connections between medical education and e-health will continue to be problematic. We hope that this paper will lead to an improved understanding of these problems and will serve to advance the discourse on how medical education should engage with the world of e-health and the world of e-health with medical education.

Stakeholder Perspectives on an Inpatient Hypoglycemia Informatics Alert: Mixed Methods Study.

BACKGROUND: Iatrogenic hypoglycemia is a common occurrence among hospitalized patients and is associated with poor clinical outcomes and increased mortality. Clinical decision support systems can be used to reduce the incidence of this potentially avoidable adverse event. OBJECTIVE: This study aims to determine the desired features and functionality of a real-time informatics alert to prevent iatrogenic hypoglycemia in a hospital setting. METHODS: Using the Agency for Healthcare Research and Quality Five Rights of Effective Clinical Decision Support Framework, we conducted a mixed methods study using an electronic survey and focus group sessions of hospital-based providers. The goal was to elicit stakeholder input to inform the future development of a real-time informatics alert to target iatrogenic hypoglycemia. In addition to perceptions about the importance of the problem and existing barriers, we sought input regarding the content, format, channel, timing, and recipient for the alert (ie, the Five Rights). Thematic analysis of focus group sessions was conducted using deductive and inductive approaches. RESULTS: A 21-item electronic survey was completed by 102 inpatient-based providers, followed by 2 focus group sessions (6 providers per session). Respondents universally agreed or strongly agreed that inpatient iatrogenic hypoglycemia is an important problem that can be addressed with an informatics alert. Stakeholders expressed a preference for an alert that is nonintrusive, accurate, communicated in near real time to the ordering provider, and provides actionable treatment recommendations. Several electronic medical record tools, including alert indicators in the patient header, glucose management report, and laboratory results section, were deemed acceptable formats for consideration. Concerns regarding alert fatigue were prevalent among both survey respondents and focus group participants. CONCLUSIONS: The design preferences identified in this study will provide the framework needed for an informatics team to develop a prototype alert for pilot testing and evaluation. This alert will help meet the needs of hospital-based clinicians caring for patients with diabetes who are at a high risk of treatment-related hypoglycemia.

Plastic modification of human cornea in vivo: applications to clinical refractive procedures.

PURPOSE: The purpose of this report is to quantify how pressure applied to the human cornea, either physiological or intentional, affects its curvature. In particular, how pneumatic procedures flatten the central cornea and keep it flat over time, thereby decreasing the patient's myopia. METHODS: A viscoelastic model is developed for plastic deformation which gives us the basic governing equations of the elastic and plastic strain of corneal stroma. The model is applied to data from corneas of six patients who underwent pneumatic keratology (NEumatica Keratologia) to reduce their myopia. RESULTS: The model shows corneal dimensional stability for long periods of time after NEumatica Keratologia that decay with an exponential time constant. Separate equations are developed that relate corneal plastic strain to the pressure applied and its duration ε = σ 0 t 1/η 1, to change in refraction ε = 2 × ΔRefr, to keratometry radius increase ε = ΔR/R, and to corneal thinning ε = sqr (Δh/h). The average values obtained for ε from the patients' data are 3%, 3.2%, 3%, and 2.6%, respectively, all in remarkable agreement. The average refraction change is found to remain stable at ΔRefr = +1.67D ± 5.2%. Clinical data yield good agreement of theory and treatment results. CONCLUSIONS: The model proposed is a good description of NEumatica Keratologia outcomes. Practical applications include the long-term stable correction of myopia with refractive procedures. High myopia subjects can benefit from this procedure because NEumatica Keratologia corrects and protects the central cornea radius by stretching the peripheral cornea.

Virtual patients come of age.

On-screen simulations of clinical settings have been used for educational purposes since the 1970s. Despite this, it is only now that these 'virtual patients' are increasingly forming a part of the medical education mainstream. Enabling factors for these changes include a requirement for more assured clinical encounters, changes in patient availability (in particular, in tertiary contexts), diminishing technical and cost barriers and ongoing changes in educational practices as a whole. This special edition of Medical Teacher presents a number of papers covering key factors in the development, use and evaluation of virtual patients in contemporary medical education practice.

Evaluation of a Training Program to Improve Organizational Capacity for Health Systems Analytics.

OBJECTIVE: The Leadership in Analytics and Data Science (LEADS) course was evaluated for effectiveness. LEADS was a 6-month program for working biomedical and health informatics (BMHI) professionals designed to improve analytics skills, knowledge of enterprise applications, data stewardship, and to foster an analytics community of practice through lectures, hands-on skill building workshops, networking events, and small group projects. METHODS: The effectiveness of the LEADS course was evaluated using the Kirkpatrick Model by assessing pre- and postcourse knowledge, analytics capabilities, goals, practice, class lecture reaction, and change in the size of participant professional networks. Differences in pre- and postcourse responses were analyzed with a Wilcoxon signed rank test to determine significance, and effect sizes were computed using a z-statistic. RESULTS: Twenty-nine students completed the course with 96% of respondents reporting that they were "very" or "extremely" likely to recommend the course. Participants reported improvement in several analytics capabilities including Epic data warehousing (p = 0.017), institutional review board policy (p = 0.005), and data stewardship (p = 0.007). Changes in practice patterns mirrored those in self-reported capability. On average, the participant professional network doubled. CONCLUSION: LEADS was the first course targeted to working BMHI professional at a large academic medical center to have a formal effectiveness evaluation be published in the literature. The course achieved the goals of expansion of BMHI knowledge, skills, and professional networks. The LEADS course provides a template for continuing education of working BMHI professionals.

Development and Implementation of a Subcutaneous Insulin Clinical Decision Support Tool for Hospitalized Patients.

BACKGROUND: Insulin is one of the highest risk medications used in hospitalized patients. Multiple complex factors must be considered in determining a safe and effective insulin regimen. We sought to develop a computerized clinical decision support (CDS) tool to assist hospital-based clinicians in insulin management. METHODS: Adapting existing clinical practice guidelines for inpatient glucose management, a design team selected, configured, and implemented a CDS tool to guide subcutaneous insulin dosing in non-critically ill hospitalized patients at two academic medical centers that use the EpicCare® electronic medical record (EMR). The Agency for Healthcare Research and Quality (AHRQ) best practices in CDS design and implementation were followed. RESULTS: A CDS tool was developed in the form of an EpicCare SmartForm, which generates an insulin regimen by integrating information about the patient's body weight, diabetes type, home and hospital insulin requirements, and nutritional status. Total daily recommended insulin doses are distributed into respective basal and nutritional doses with a tailored correctional insulin scale. Preimplementation, several approaches were used to communicate this new tool to clinicians, including emails, lectures, and videos. Postimplementation, a support team was available to address user technical issues. Feedback from stakeholders has been used to continuously refine the tool. Inclusion of the programming in the EMR vendor's community library has allowed dissemination of the tool outside our institution. CONCLUSIONS: We have developed an EMR-based tool to guide SQ insulin dosing in non-critically ill hospitalized patients. Further studies are needed to evaluate adoption and clinical effectiveness of this intervention.

Sharing innovation: the case for technology standards in health professions education.

Information technologies have provided fertile ground for innovation in healthcare education, but too often these innovations have been limited in scope and impact. One way of addressing these limitations is the development of common and open technology standards to scale innovation across organizational boundaries. Research on the diffusion of standards indicates that environmental forces, such as regulatory changes, top-down management support, and feasibility are key determinants of standards adoption. This paper describes the perspective and work of MedBiquitous, the only internationally recognized standards body in healthcare education. Many innovators are implementing MedBiquitous healthcare education standards to effect change within and across organizations. In a resource-constrained and knowledge intensive domain such as healthcare education, collaboration is an imperative. Technology standards are essential to raise the quality of healthcare education and assessment in a cost-effective manner.

Juvenile Myopia. Predicting the Progression Rate.

Regression plots are generated showing the strong correlation of myopia onset age with its progression rate, r = -0.77, p<0.0025, and strong correlation of accumulated myopia 5 years after onset, r = -0.78, p < 0.001. Theory is confirmed, with all subjects showing excellent correlation coefficients, = -0.971, p < 0.005. Myopia progression rates vary from 0.2 to 1.0 diopters (D) per year from one individual to the next. Age of onset for myopia is 10.6 yrs. +/-5.4 yrs. Initial refraction at onset is -1.14 D +/-0.55 D. Practical applications of this work include delaying correction for myopes, and juvenile susceptibility to myopia at various age levels. Feedback Theory predicts the results.

REVIEW. +2 to +3 D. Reading Glasses to Prevent Myopia.

Basic control theory equations are developed showing classical exponential system response of refraction vs. time R(t), with a characteristic system time constant, in response to a negative (-) step change of near work environmental conditions. Statistical analysis of retrospective data from 226 subjects is presented. It is shown that reasonable significance levels p < 0.001 can be obtained from relatively small sample sizes, over short time intervals. Details from preliminary experimental design using reading glasses at the U.S. Naval Academy at Annapolis are discussed. The conclusion is that positive (+) Add lenses, used as reading glasses during study, can prevent the development of myopia of college students in pilot training.

Progressive Myopia and Lid Suture Myopia are Explained by the Same Feedback Process: a Mathematical Model of Myopia.

OBJECTIVE: Progressive myopia in humans and lid-sutured myopia in primates have been considered to be different processes. This report seeks to establish the connection between progressive myopia in humans and lid suture myopia in macaque monkeys. METHODS: We followed the axial length of 4 lid-sutured macaque monkeys over an 18 month period. Their axial length is directly related to myopia. We also studied the myopia progression in corrected human subjects. Macaques and humans exhibit a linear time course of myopia progression when lid-sutured or corrected with lenses, respectively. RESULTS: A linear progression is observed in lid-sutured eyes of four macaques, r = 0.94, p < 0.05. Human progressive myopia and lid-suture myopia can be modeled by the same feedback process. In both cases the functional equivalent is the opening of the feedback loop. CONCLUSIONS: The open loop feedback process predicts a linear progression of myopia. This prediction was confirmed in human subjects and it is now confirmed in our macaque subjects. This process also explains the very rapid rate of myopia progression of lid sutured eyes.

Exponential prevalence and incidence equations for myopia.

BACKGROUND: This project relates prevalence-time data, incidence rate data, age of onset, system plateau level and system time constant, using exponential equations, as they apply to progressive myopia, useful over several decades. METHODS: Cross-sectional refractive data is analysed for nine studies with a total number of subjects at 444.6 K (345, 981, 7.6 K, 39, 421 K, 383, 2 K, 12 K, 255), with ages ranging from five to 39 years. Basic exponential equations allow calculation of the prevalence versus time function Pr(t) as a percentage and the incidence rate function In(t) (percentage per year), system time constant t0 (years), onset age t1 (years) and saturation plateau level (percentage). RESULTS: The prevalence of myopia as a function of time Pr(t) (years) and incidence of myopia as a function of time In(t) (percentage per year) are continuously generated and compared with prevalence/incidence data from various reports investigating student populations. For a general medical condition, typical values for time constant t0 may range from one week to five years, depending on the health condition. Typical plateau levels for myopia may range from 35 to 95 per cent. Herein, data from nine demographic studies of myopia are analysed for prevalence Pr(t) with an accuracy within 14 per cent and incidence In(t) within 2.6 per cent per year, onset t1 = 1.5 years, time constant t0 = 4.5 year. By comparison, linear regression can predict the prevalence of myopia Pr(t) within 11 per cent and estimates a constant incidence rate for myopia In(t) of 4.7 per cent per year (95 per cent CI: 2.1 to 7.3 per cent per year]. CONCLUSIONS: The initial incidence rate at onset age In(t1) and system time constant t0 are inversely related. For myopia, onset age, time constant and saturation plateau level are fundamental system parameters derived from age-specific prevalence and incidence data.

Surgical advances in bladder cancer: at what cost?

Bladder cancer is the most expensive cancer to treat from diagnosis to death. Frequent disease recurrence, intense follow-up, and expensive, invasive techniques for diagnosis and treatment drive these costs for non-muscle invasive bladder cancer. Fluorescence cystoscopy increases the detection of superficial bladder cancer and reduces costs by improving the quality of resection and reducing recurrences. Radical cystectomy with intestinal diversion is the mainstay of treatment of invasive disease; however it is associated with substantial cost and morbidity. Increased efforts to improve the surgical management of bladder cancer while reducing the cost of treatment are increasingly necessary.

Cardiac valve replacement in human immunodeficiency virus-infected patients.

BACKGROUND: Valve replacement in human immunodeficiency virus (HIV)-infected patients is being performed with increasing frequency, but the early and late results in these immunocompromised patients are not known. METHODS: A 10-year retrospective clinical review was undertaken; patients and their physicians were contacted for follow-up clinical status. RESULTS: Twenty-two HIV-infected patients underwent valve replacement between 1990 and 1999, with no operative or hospital deaths. Mean patient age was 37.6 years; 15 were men. Indications for operation were heart failure in 59% (13/22) and sepsis in 91% (20/22). There were 12 aortic valve replacements, seven mitral valve replacements, and three double valve replacements. Mechanical valves were used in 11, bioprostheses in seven, and homografts in four. Follow-up information was available in 20 of 22 patients (84%). At mean follow-up of 5 years, there were 10 late deaths, due to: intracerebral hemorrhage (2), heart failure (2), unknown cause (2), renal failure (1), AIDS (1), sepsis (1) and endocarditis (1). Of the 20 patients with active preoperative endocarditis, 4 (20%) developed recurrent endocarditis; freedom from recurrent endocarditis was 83% at 1 year. Intravenous drug abuse was reported in 16 patients; survival among these patients was 94% at 1 month and 50% at 5 years. Recurrent endocarditis was only seen in patients with continued intravenous drug abuse. CONCLUSIONS: Valve replacement in HIV-infected patients has low operative risk, but late results are poor when HIV infection is associated with intravenous drug abuse, probably due to immunocompromise and continued high-risk behavior.

Aortic root replacement in 271 Marfan patients: a 24-year experience.

BACKGROUND: The introduction of composite graft repair of aortic root aneurysm by Hugh Bentall in 1968 promised Marfan patients the choice for a normal life expectancy. We performed our first Bentall composite graft procedure in 1976 and herein report our 24-year experience with 271 Marfan patients. METHODS: Between September 1976 and August 2000, 232 Marfan patients had a composite graft replacement of the aortic root, 15 patients received a homograft, and 24 had a valve-sparing procedure. RESULTS: Two hundred thirty-five Marfan patients underwent elective aortic root replacement with no 30-day mortality. Two early deaths occurred among 36 patients who underwent urgent or emergent operation. Eighty-three percent of patients in this series are currently alive. The actuarial freedom from thromboembolism, endocarditis, and reoperation on the residual aorta 20 years postoperatively was 93%, 90%, and 74%. Twenty-four patients have undergone valve-sparing procedures with encouraging results. CONCLUSIONS: Elective aortic root replacement for Marfan patients can be performed with low operative risk. Elective repair before the aortic root reaches 6 cm in diameter is recommended to minimize risk of dissection and rupture.