The Structure of Clinical Ethical Decision-Making: A Hospital System Needs Assessment.

Bioethical dilemmas can emerge in research and clinical settings, from end-of-life decision-making to experimental therapies. The COVID-19 pandemic raised serious ethical challenges for healthcare organizations, highlighting the need to conduct needs assessments of the bioethics infrastructures of healthcare organizations. Clinical ethics committees (CECs) also create equitable policies, train staff on ethics issues, and play a consultative role in resolving the difficulty of complex individual cases. The main objective of this project was to conduct a needs assessment of the bioethics infrastructure within a comprehensive hospital system. A cross-sectional anonymous online survey, including quantitative and qualitative formatted questions. The survey was sent to five key leaders from the organization's hospitals. Survey questions focused on the composition, structure, function, and effectiveness of their facilities' bioethics infrastructure and ethics-related training and resources. Positive findings included that most facilities have active CECs with multidisciplinary membership; CECs address critical issues and encourage team members to express clinical ethics concerns. Areas of concern included uncertainty about how CECs function and the process for resolving clinical ethics dilemmas. Most reported no formal orientation process for CEC members, and many said there was no ongoing ethics education process. The authors conclude that if CECs are a critical institutional resource where the practice of medicine and mission intersect, having well-functioning ethics committees with trained and oriented members demonstrates an essential commitment to the mission. The survey revealed that more needs to be done to bolster the bioethics infrastructure of this institution.

Facilitadores y barreras para el uso de la práctica basada en evidencia / Facilitators and barriers to the use of evidence-based practice / Facilitadores e barreiras ao uso de práticas baseadas em evidências

Objetivo: Conocer los facilitadores y barreras para el uso de la práctica basada en evidencia (PBE) en profesionales de enfermería que laboran en el área clínica. Método: Estudio cuali-tativo de tipo exploratorio descriptivo, con análisis de discurso, se realizaron 6 grupos focales conformados por 3 a 7 participantes para un total de 32 personas, se utilizó un muestreo inten-cional; en promedio fueron grabados entre 60 a 90 minutos por grupo focal. Para el análisis se empleó la fragmentación, codificación y categorización de las entrevistas obteniendo categorías temáticas, subcategorías y códigos a partir del uso del programa Atlas Ti versión 8. Resultados: El 69 % de los entrevistados respondió que el pregrado o posgrado habían recibido algún tipo de formación en PBE, la principal fuente de información cuando tienen alguna duda en la práctica clínica son los protocolos institucionales o los compañeros con más experiencia. Los facilitado-res identificados en este estudio fueron: tiempo para investigar, formación en PBE, iniciativa, grupos de investigación y compañeros; las barreras fueron: falta de apoyo institucional, poca formación en PBE, falta de tiempo, idioma, desmotivación profesional y el rechazo frente al cambio. Conclusiones: Se describen los facilitadores y barreras que presentan los profesionales de enfermería que laboran en el área clínica. Sin embargo se requieren investigaciones adicion-ales que permitan reconocer el fenómeno desde otras perspectivas en el contexto Colombiano y latinoamericano

Objective: To find out the facilitators and barriers to the use of evidence-based practice (EBP) in nursing professionals working in the clinical area. Method: Qualitative descrip-tive exploratory study, with discourse analysis, 6 focus groups were carried out with 3 to 7 participants for a total of 32, a purposive sampling was used; an average of 60 to 90 minutes were recorded per focus group. For the analysis we used the fragmentation, coding and cate-gorisation of the interviews obtaining thematic categories, subcategories and codes from the use of Atlas Ti version 8. Results: 69 % of the interviewees responded that the undergraduate or postgraduate had received some kind of training in EBP, the main source of information when they have any doubt in clinical practice are the institutional protocols or colleagues with more experience. Facilitators identified in this study were: time to investigate, training in EBP, initiative, research groups and peers; barriers were: lack of institutional support, little training in EBP, lack of time, language, professional demotivation and rejection in the face of change. Conclusions: The facilitators and barriers presented by nursing professionals working in the clinical area are described. However, further research is needed to recognise the phenomenon from other perspectives in the Colombian and Latin American context.

Objetivo: Descobrir os facilitadores e as barreiras ao uso da prática baseada em evidências (PBE) em profissionais de enfermagem que atuam na área clínica. Método: Estudo exploratório descritivo qualitativo, com análise de discurso; foram realizados 6 grupos focais com 3 a 7 participantes, totalizando 32; foi usada uma amostragem intencional; foi registrada uma média de 60 a 90 minutos por grupo focal. Para a análise utilizou-se a fragmentação, codificação e categorização das entrevistas obtendo-se categorias temáticas, subcategorias e códigos a partir da utilização do Atlas Ti versão 8. Resultados: 69% dos entrevistados responderam que a grad-uação ou pós-graduação havia recebido algum tipo de treinamento em PBE, a principal fonte de informação quando têm alguma dúvida na prática clínica são os protocolos institucionais ou colegas com mais experiência. Os facilitadores identificados neste estudo foram: tempo para in-vestigar, treinamento em PBE, iniciativa, grupos de pesquisa e colegas; as barreiras foram: falta de apoio institucional, pouco treinamento em PBE, falta de tempo, idioma, desmotivação profis-sional e rejeição diante de mudanças. Conclusões: São descritos os facilitadores e as barreiras apresentados pelos profissionais de enfermagem que trabalham na área clínica. No entanto, são necessárias mais pesquisas para reconhecer o fenômeno de outras perspectivas no contexto co-lombiano e latino-americano

Characterization of Shallow Ground in Railway Embankments Using Surface Waves Measured by Dark Fiber Optics Sensors: A Case Study.

For the maintenance of railways on soft soils, accurate knowledge of the subsoil conditions is essential. Soft soils at shallow depths have high variability; thus, high spatial resolution is required. Spare telecommunication fiber-optic cables, known as dark fiber, can be used as an array of sensors to measure waves generated by running trains, which offers a unique opportunity to characterize shallow soils at high spatial resolution. We used dark fiber to measure seismic waves generated by running trains and implemented a seismic interferometry technique to retrieve surface waves. We evaluated the reliability of selected parts of the recorded signals split as bow waves (the train approaching the fiber), train waves (the train passing alongside the fiber), and tail waves (the train leaving the fiber) to retrieve broad-band surface waves. The analysis was performed in two distinctive zones. Zone I consists of a thick-soft (2.0-6.0 m thickness) layer, and Zone II consists of a thin-soft (less than 2.0 m thickness) layer, both overlaying a "stiffer" sand layer. At Zone I, train waves yielded the best results in revealing the thick-soft layer. At Zone II, the bow waves yielded clear high-frequency energy, revealing the overall soil structure but without identifying the shallow thin-soft layer.

Catecholaminergic Polymorphic Ventricular Tachycardia and Gene Therapy: A Comprehensive Review of the Literature.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited channelopathy. In this review, we summarize the epidemiology, pathophysiology, clinical characteristics, diagnostics, genetic mutations, standard treatment, and the emergence of potential gene therapy. This inherited cardiac arrhythmia presents in a bimodal distribution with no association between sex or ethnicity. Six different CPVT genes have been identified, however, most of the cases are related to a heterozygous, gain-of-function mutation on the ryanodine receptor-2 gene (RyR2) and calsequestrin-2 gene (CASQ2) that causes delayed after-depolarization. The diagnosis is clinically based, seen in patients presenting with syncope after exercise or stress-related emotions, as well as cardiac arrest with full recovery or even sudden cardiac death. Standard treatment relies on beta-blockers, with add-on therapy, flecainide, and cardiac sympathetic denervation as second-line treatments. An implantable cardioverter-defibrillator is indicated for patients who have suffered a cardiac arrest. Potential gene therapy has emerged in the last 20 years and accelerated because of associated viral vector application in increasing the efficiency of prolonged cardiac gene expression. Nevertheless, human trials for gene therapy for CPVT have been limited as the population is rare, and an excessive amount of funding is required.

Entorno laboral de los enfermeros de un hospital público de Colombia / Work environment of nurses in a public colombian hospital

Introducción: El entorno laboral de los profesionales de enfermería hospitalarios y su impacto en resultados no ha sido explorado en Colombia. Esta investigación busca describir las características del entorno laboral de los profesionales de enfermería de un hospital público universitario colombiano y determinar su asociación con las características sociodemográficas y con resultados para el enfermero, el paciente y la institución. Método: Estudio descriptivo exploratorio. Se invitó a participar a los 139 enfermeros clínicos de la institución. Se remitió el formulario por RedCap, con preguntas sociodemográficas y laborales, el instrumento ENLASA-Enfermería y preguntas de resultados. De los datos sociodemográficos y laborales se obtuvieron frecuencias y porcentajes. Se empleó el método de Dalenius-Hodges para determinar el puntaje en el cual se consideraba el entorno laboral saludable. Para analizar las asociaciones entre las características sociodemográficas y laborales, los puntajes de ENLASA-Enfermería y los resultados se usaron coeficiente de contingencia, Phi y V de Cramer. Resultados: La tasa de respuesta fue 84%. El puntaje global sugiere que el entorno laboral es saludable. La dimensión de componentes estructurales organizacionales es considerada no saludable (58,3048/100); mientras la de procesos organizaciones es considerada saludable (68,1256/100). Las subdimensiones con más bajos puntajes fueron: políticas de recursos humanos (62,2960/100), planeación de recursos de enfermería (42,9487), y remuneración (52,7778). En la dimensión de procesos organizacionales la autonomía clínica obtuvo el más bajo y el único puntaje que la clasifica como aspecto no saludable (52,6709). Conclusiones: Se plantea la necesidad de promover entornos laborales saludables, trabajar en políticas y planeación del recurso humano en enfermería y avanzar en la investigación en torno a este asunto, para apoyar decisiones de políticas públicas y organizacionales. (AU)

Introduction: The work environment of hospital nurses and its impact on results have not been explored in Colombia. This research seeks to describe the characteristics of the work environment of nurses in a Colombian public hospital and to determine their association with sociodemographic characteristics and with results for the nurse, the patient and the institution. Method: Exploratory descriptive study. The 139 clinical nurses from the institution were invited to participate. The form was sent by RedCap, with sociodemographic and employment questions, the ENLASA-Nursing instrument, and results questions. Frequencies and percentages were obtained from the sociodemographic and employment data. The Dalenius-Hodges method was used to determine the score in which the healthy work environment was considered. To analyze the associations between sociodemographic and occupational characteristics, ENLASA-Nursing scores, and outcomes, the contingency coefficient, Phi, and Cramer's V were used. Results: The response rate was 84%. The overall score suggests that the work environment is healthy. The dimension of organizational structural components is considered unhealthy (58.3048/100); that of organizational processes is considered healthy (68.1256/100). The subdimensions with the lowest scores were: human resources policies (62.2960/100), nursing resource planning (42.9487), and remuneration (52.7778). In the organizational process dimension, clinical autonomy obtained the lowest and the only score that classifies it as an unhealthy aspect (52.6709). Conclusions: There is a need to promote healthy work environments, work on policies and planning of human resources in nursing, and advance research on this matter, to support national and organizational policy decisions. (AU)

Outbreak of Locally Acquired Mosquito-Transmitted (Autochthonous) Malaria - Florida and Texas, May-July 2023.

Eight cases of locally acquired, mosquito-transmitted (i.e., autochthonous) Plasmodium vivax malaria, which has not been reported in the United States since 2003, were reported to CDC from state health departments in Florida and Texas during May 18-July 17, 2023. As of August 4, 2023, case surveillance, mosquito surveillance and control activities, and public outreach and education activities continue in both states. U.S. clinicians need to consider a malaria diagnosis in patients with unexplained fever, especially in areas where autochthonous malaria has been recently reported, although the risk for autochthonous malaria in the United States remains very low. Prompt diagnosis and treatment of malaria can prevent severe disease or death and limit ongoing transmission to local Anopheles mosquitoes and other persons. Preventing mosquito bites and controlling mosquitoes at home can prevent mosquitoborne diseases, including malaria. Before traveling internationally to areas with endemic malaria, travelers should consult with a health care provider regarding recommended malaria prevention measures, including potentially taking malaria prophylaxis. Malaria is a nationally notifiable disease; continued reporting of malaria cases to jurisdictional health departments and CDC will also help ensure robust surveillance to detect and prevent autochthonous malaria in the United States.

The Perfect Storm: A Case of Rapid-Onset Obesity With Hypoventilation, Hypothalamic, Autonomic Dysregulation, Neuroendocrine Tumor (ROHHADNET) With Heart Failure, Narcolepsy, and a Rare Location of a Pelvic Neuroendocrine Tumor.

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) syndrome is a rare disease of concurrent respiratory dysfunction and autonomic dysregulation with endocrine abnormalities. ROHHADNET includes ROHHAD plus coexisting neuroendocrine tumors (NETs). We describe an eight-year-old boy, who originally presented at four years of age with rapid weight gain and hyperhidrosis and who developed mild obstructive sleep apnea (OSA). His clinical course was eventually complicated by hypoxic respiratory failure requiring admission to the pediatric intensive care unit (PICU). Echocardiogram at that time demonstrated dilated cardiomyopathy left ventricular ejection fraction (LVEF) of 28% at time of admission. His respiratory failure persisted despite average volume-assured pressure support (AVAPS) around the clock leading to tracheostomy placement for cardiopulmonary support. He also demonstrated autonomic instability with multiple pituitary hormone deficiencies. Computed tomography (CT) imaging of the abdomen and pelvis demonstrated a presacral soft tissue mass consistent with a tumor of neural crest origin. Daytime somnolence and confusion progressed and a low cerebrospinal fluid hypocretin level revealed a diagnosis of narcolepsy type 1.

Ser docentes en un hospital universitario: una mirada desde el desarrollo de capacidades / Being a teacher in a university hospital: from a competences development perspective

Introducción: los docentes de las ciencias de la salud deben desarrollar ciertas capacidades para formar a los profesionales del área en los entornos hospitalarios, para ello deben conocer las dinámicas y comportamientos de los relevos generacionales, así como los avances tecnológicos derivados de la globalización y la importancia de incluirlos como herramientas pedagógicas. Objetivo: responder la pregunta ¿Cómo se puede ser docente en un hospital universitario? Discusión y conclusiones: se construyeron unas propuestas sobre las capacidades que el docente debe desarrollar, como investigar, tener en cuenta un modelo pedagógico, un pensamiento crítico y la capacidad de innovar, para permitir su funcionalidad y poder cumplir su misión en la formación de los futuros profesionales de la salud

Introduction: health sciences teachers must develop certain skills to train health professionals within a hospital environment. To this end, they should be aware of the dynamics and trends of generational differences, as well as the technological advances derived from globalization and the importance of their incorporation as pedagogical tools. Objective: to answer the question: How can one be a teacher in a university hospital? Discussion and conclusions: some proposals were made regarding the skills that teachers should gain, such as carrying out research, following a pedagogical model, applying critical thinking, and having innovation capacity, to allow their functionality and enable the fulfillment of their mission in training future health professionals.

Approach for designing thick cemented doublet lenses based on the caustic surface.

A new, to the best of our knowledge, method for designing a thick-lens achromatic doublet based on the concept of a caustic surface to correct both third- and fifth-order spherical aberration is presented. We consider two different wavelengths brought into coincidence at the back focal length instead of the effective focal length as it is usually done, to calculate the radii of curvature assuming predefined values for axial thicknesses and their indices of refraction for both lenses. Alternatively, we apply Taylor's series around the optical axis, and to vanish the approximate caustic surface, we obtain the values for the conic constants, which reduce at third- and fifth-order spherical aberration. Two designs for cemented doublets are provided assuming that the lenses are cemented. Finally, we propose a method to qualitatively test doublet lenses by using null screens, considering to place the detection plane at arbitrary positions.

Adverse Soft-Tissue Reaction After Ceramic-On-Ceramic Bearing Fracture Mimicking a Periprosthetic Joint Infection.

Prosthetic failure secondary to bearing fracture remains a potential complication in ceramic-on-ceramic total hip arthroplasty. We report the unusual presentation of a ceramic component fracture of a total hip arthroplasty performed 17 years ago that mimicked a periprosthetic joint infection. This case was managed based on the current guidelines and algorithms recommended for periprosthetic joint infection management. Histologic examination of periprosthetic tissue revealed an adverse inflammatory soft-tissue reaction to the ceramic fragments released from the fracture site. Our case highlights a misleading, inflammatory acute response usually associated with an infectious process corresponding to an adverse soft-tissue reaction. High clinical suspicion and a systematic approach are essential to address these deceiving clinical scenarios.

Refracting and reflecting interfaces transforming a given wavefront into another one.

The aim of this work is threefold. First, following Luneburg and using our own notation, we review the Cartesian ovals. Second, we obtain analytical expressions for the reflecting and refracting surfaces that transform a prescribed smooth two-dimensional wavefront into a spherical one. These results are applied to show that the reflecting surface that connects a plane wavefront to a spherical one is a parabolical surface, and we design a lens, with two freeform surfaces, that transforms a spherical wavefront into another spherical one. These examples show that our equations provide the well-known solution for these problems, which is given by the Cartesian ovals method. Third, we present a procedure to obtain exact expressions for the refracting and reflecting surfaces that connect two given arbitrary wavefronts; that is, by assuming that the optical path length between two points on the prescribed wavefronts is given by the designer the refracting and reflecting surfaces we are looking for are determined by a set of two algebraic equations, which in the general case have to be solved in a numerical way. These general results are applied to compute the analytical expressions for the reflecting and refracting surfaces that transform a parabolical initial wavefront into a plane one.

Ronchi-Hartmann type null screens for testing a plano-freeform surface with a detection plane inside a caustic surface.

We have implemented an exact ray trace through a plano-freeform surface for an incident plane wavefront. We obtain two caustic surfaces and provide the critical points related to the ray tracing process. Additionally, we study the propagation of the refracted wavefronts through the plane-curved surface. Finally, by using the Ronchi-Hartmann type null screen and placing the detection plane within the caustic region, we have evaluated the shape of a plano-freeform optical surface under test, obtaining an RMS difference in sagitta value of 6.3 µm.

Autoetnografía y reflexiones en la pandemia por COVID-19 / Autoethnography and reflections on the COVID-19 pandemic / Antropologia cultural e reflexões na pandemia pela COVID-19

La pandemia de la COVID 19 es un problema mundial que no solo ha causado muertes y enfermos, sino que ha afectado la vida de los trabajadores de la salud. Para este artículo se desarrolla un relato a través de la autoetnografía, lo que permite hacer un acercamiento a los cambios generados dentro de una institución en salud a causa de esta situación, permitiendo trasladar las experiencias de la práctica a la teoría y analizar situaciones de lo sucedido en la atención de pacientes infectados. El objetivo es describir algunas vivencias de profesionales y auxiliares de la enfermería sobre la atención de pacientes con COVID-19 en un hospital universitario de Colombia y lo que implica el cuidado de la enfermería en una pandemia, usando los metaparadigmas y evidenciando el impacto de todos estos cambios en las personas y en la sociedad en general. Conclusión: los profesionales de la enfermería siempre estarán en primera línea, brindando las mejores experiencias de cuidado a las personas, sus familias y además acompañándolos en los procesos de nacer, crecer, vivir y morir. Aunque exista tecnología, pandemias, problemas sociales en el mundo, la enfermería seguirá participando, expresando sus sentires y trascendiendo en la vida de las personas con los actos de cuidado humano.

The COVID 19 pandemic is a global issue that not only has caused deaths and contagion, but also has affected the life of healthcare workers. For this article a narrative is performed through autoethnography, approaching the changes within a health institution generated by this situation, allowing to transfer the practice experiences to the theory and analyze situa-tions during the assistance of infected patients. The objective is to describe some of the ex-periences from the professionals and nursing assistants about the assistance of patients with COVID-19 in a university hospital in Colombia and what implies the nursing care implies during a pandemic, using the metaparadigms and evidencing the impact of all these changes in people and society in general. Conclusion: The nursing professionals will always be on the first line, providing the best care experience for people, their families as well as accompany-ing them during the processes of birth, growth, life and death. Although there are technolo-gies, pandemics, social issues around the globe, nursing will keep participating, expressing its feelings and transcending in the lives of people as actors of human care

A pandemia pela COVID-19 é um problema mundial que não só tem gerado morte e doença, além disso tem afetado a vida dos trabalhadores do setor saúde. Para esse artigo desen-volveu-se um relato através de antropologia cultural, permitindo fazer uma aproximação às mudanças geradas no interior da instituição de saúde como consequência dessa situação, permitindo trasladar a experiência da prática à teoria e analisar o acontecido no atendimento aos sujeitos infetados. O objetivo é descrever algumas vivências dos profissionais e a equipe técnica de enfermagem sobre o atendimento de pacientes com a COVID-19 num hospital escola de Colômbia e as suas implicações no cuidado de enfermagem numa pandemia, usan-do os metaparadigmas e evidenciando o impacto de todas essas mudanças nas pessoas e na sociedade no geral. Conclusão: os profissionais de enfermagem sempre estarão na primeira linha, prestando as melhores experiências de cuidado às pessoas, as suas famílias e além disso, acompanhando os processos de nascer, crescer, viver e morrer. Embora exista tecn-ologia, pandemias e problemas sociais no mundo, a enfermagem continuara participando , expressando os seus sentimentos e transcendendo na vida das pessoas com os atos de cuidado humano

Fabrication of polymer and carbon polyhedra through controlled cross-linking and capillary deformations.

Fabrication of polymer polyhedral structures is achieved by first producing origami sheets with dissimilar stiffness levels at their folds and faces via multi-step photolithography. Subsequent capillary folding of the sheets towards permanently folded target shapes is realized by thermally controlling, simultaneously, the compliance of the sheets and the volume of the deposited droplets. This fabrication method allows us to create millimeter and sub-millimeter polyhedral structures with arbitrary levels of folding, to manufacture permanently folded polymer polyhedra using single-material monolayer sheets, and to produce carbon shapes from these carbon-rich polymer polyhedra through pyrolysis.

Sagittal and tangential foci produced by tilted plane wavefronts refracted through simple lenses.

We study the formation of caustic and wavefront surfaces produced by a tilted plane wavefront propagating through spherical positive lenses. The shape of the caustic surface is a function of the indices of refraction, the geometrical parameters of the lens involved in the process of refraction, and the obliquity angle with respect to the optical axis, as we expect. We provide exact and approximate analytic equations for tangential and sagittal focal surfaces and also for Petzval field curvature considering arbitrary lenses.

A network of insulin peptides regulate glucose uptake by astrocytes: Potential new druggable targets for brain hypometabolism.

Astrocytes are major players in brain glucose metabolism, supporting neuronal needs on demand through mechanisms that are not yet entirely clear. Understanding glucose metabolism in astrocytes is therefore of great consequence to unveil novel targets and develop new drugs to restore brain energy balance in pathology. Contrary to what has been held for many years, we now present evidence that insulin, in association with the related insulin-like growth factor I (IGF-I) modulates brain glucose metabolism through a concerted action on astrocytes. Cooperativity of insulin and IGF-I relies on the IGF-I receptor (IGF-IR), that acts as a scaffold of Glucose Transporter 1 (GluT1) regulating its activity by retaining it in the cytoplasm or, in response to a concerted action of insulin and IGF-I, translocating it to the cell membrane. Regulated translocation of GluT1 to the cell membrane by IGF-IR involves an intricate repertoire of protein-protein interactions amenable to drug modulation, particularly by interfering with IGF-IR/GluT1 interactions. We propose that this mechanism accounts for a substantial proportion of basal and regulated glucose uptake by astrocytes as GluT1 is the major glucose transporter in these brain cells. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'

Toughness amplification in copper/epoxy joints through pulsed laser micro-machined interface heterogeneities.

This work addresses the mechanics of debonding along copper/epoxy joints featuring patterned interfaces. Engineered surface heterogeneities with enhanced adhesion properties are generated through pulsed laser irradiation. Peel tests are carried out to ascertain the effect of patterns shape and area fraction on the mechanical response. Experimental results are evaluated with the support of three-dimensional finite element simulations based on the use of cohesive surfaces. Results discussion is largely framed in terms of effective peel force and energy absorbed to sever the samples. It is shown that surface heterogeneities act as sites of potential crack pinning able to trigger crack initiation, propagation and arrest. Surface patterns ultimately enable a remarkable increase in the effective peel force and dissipated energy with respect to baseline homogeneous sanded interface.

Analytic conic constants to reduce the spherical aberration of a single lens used in collimated light.

We study the formation of caustic surfaces produced by conic lenses, considering a plane wavefront propagating parallel to the optical axis. The shape of the caustic can be modified by changing the parameters of the lens in such a way that if we are able to vanish the caustic, the optical system produces the sharpest diffraction-limited images. Alternatively, caustic surfaces with a large area can be applied to the design of non-imaging optical systems, with potential applications such as diffusers of light for illumination or solar concentrators. Here, we provide analytic equations for the conic constants, principal surfaces, and caustic surfaces, and also approximations at the third and fifth orders formed by conic lenses, in order to reduce the spherical aberration at these orders.

Assessing bowel preparation quality using the mean number of adenomas per colonoscopy.

INTRODUCTION: The quality of the bowel preparation directly influences colonoscopy effectiveness. Quality indicators are widely employed to monitor operator performance and to gauge colonoscopy effectiveness. Some have suggested that the enumeration of the mean number of adenomas per colonoscopy (MNA) may be a more useful measure of bowel preparation quality, but evidence of the utility of this metric is limited. The relationship between bowel preparation quality and MNA was assessed. METHODS: Records of adult patients, aged 50-74 years, who had undergone a screening colonoscopy in a 6 month period at a hospital-based endoscopy suite in New York City were examined. Excluded were those who were symptomatic or having a colonoscopy for surveillance. Patient and procedural characteristics and clinical findings were abstracted from the endoscopy database. Bowel preparation quality was recorded as excellent, good, fair and poor. Histology and size of polyps removed were gathered from pathology reports. MNA was calculated and incident rate ratios assessing the relationship between bowel preparation quality, MNA, and covariates was calculated using Poisson regression. RESULTS: A total of 2422 colonoscopies were identified; 815 (33.6%) were screening colonoscopies among average risk individuals, 50-74 years; 203 (24.9%) had ≥1 adenomas; and 666 (81.7%) had excellent/good preparation quality. Overall MNA was 0.34 [standard deviation (SD) 0.68] and MNA was greater among those >60 years [incident rate ratio (IRR) 1.89, 95% confidence interval (CI) 1.48-2.42), males (IRR 1.60, 95%CI 1.26-2.04) and those with good bowel preparation (IRR 2.54, 95%CI 1.04-6.16). Among those with ≥1 adenomas, MNA was 1.48 (SD 1.05) for excellent and 1.00 (SD 0.00) for poor quality preparation (p = 0.55). CONCLUSIONS: We found that MNA is sensitive to changes in bowel preparation with higher MNA among those with good bowel preparation compared with those with poor preparation. Our evidence suggests MNA was particularly sensitive when restricted to only those in whom adenomas were seen.

Wavefronts, caustic, ronchigram, and null ronchigrating of a plane wave refracted by an axicon lens.

The aim of this work is threefold: first we obtain analytical expressions for the wavefront train and the caustic associated with the refraction of a plane wavefront by an axicon lens, second we describe the structure of the ronchigram when the ronchiruling is placed at the flat surface of the axicon and the screen is placed at different relative positions to the caustic region, and third we describe in detail the structure of the null ronchigrating for this system; that is, we obtain the grating such that when it is placed at the flat surface of the axicon its associated pattern, at a given plane perpendicular to the optical axis, is a set of parallel fringes. We find that the caustic has only one branch, which is a segment of a line along the optical axis; the ronchigram exhibits self-intersecting fringes when the screen is placed at the caustic region, and the null ronchigrating exhibits closed loop rulings if we want to obtain its associated pattern at the caustic region.