RESUMEN
Research concerning school success and completion has grown increasingly complex with the number of proposed associated risk and needs domains. As the number of domains expands, various data analytical techniques have been employed to understand them, including the modeling of latent profiles, to better understand how risks and needs aggregate at the level of individual persons. Latent profile analysis helps identify individuals' subgroups based on salient combinations of characteristics. The present study used latent profile analysis and a systematic profile similarity approach to examine the profiles across middle and high school student cohorts. The study replicates the profiles of previous work with high school students and extends this to middle school students. We used two independent cohorts to replicate a 3-profile solution for middle and high school samples. Results supported a similar 3-profile solution for both samples, with minor discrepancies. Results are discussed with respect to the replication and extension of the 3-profile model and its application to efforts to improve outcomes for youth in both grade level cohorts.
Asunto(s)
Conducta del Adolescente , Instituciones Académicas , Humanos , Adolescente , Estudiantes , LogroRESUMEN
The Washington Assessment of the Risks and Needs of Students (WARNS) is a computer-based assessment created to help courts, schools, and youth service providers determine an adolescent's risks and needs that may lead to truancy, drop out, or delinquency from school. Users are advised to consider the WARNS total score to work with youth. A total score estimate based on fewer items than the full item set may result in less respondent burden, administration time, and fatigue, while not hindering accurate decisions. This simulation study examined the applicability and efficiency of a computerized adaptive test (CAT) to estimate a WARNS total score under a unidimensional item response theory model. The results demonstrate that the CAT provides an accurate estimate of students' risks and needs and reduces the number of items administered for each examinee compared with the existing version. Future directions and limitations of CAT development with the WARNS are discussed.
Asunto(s)
Computadores , Estudiantes , Humanos , Washingtón , Absentismo , Evaluación de NecesidadesRESUMEN
The study aimed to evaluate the effects of fibers insertion and restorative material type on the stress distribution in endocrowns with finite element analysis. Five 3D models of first mandibular molars were created and restored as follows: (1) IN: intact tooth, (2) IPS-E: tooth restored with lithium disilicat ceramic endocrowns, (3) C-E: tooth restored with composite endocrowns, (4) IPS-E + F: lithium disilicate ceramic endocrowns + fiber, (5) C-E + F: composite endocrowns + fiber. Vertical masticatory load was imitated with finite element analysis. The equivalent stress of von Mises failure criterion (mvM) was calculated. The maximum mvM stress, enamel/crown, dentin and cement were compared among models and strength of the materials. Endocrowns presented a lower mvM stress level than intact tooth. In IPS-E, the mvM stress values in the crown and dentin were higher than C-E, while the mvM stress values in cement were higher in C-E group. Fibers insertion did not affect the stress level of IPS-E and C-E groups. In IPS model, fiber showed more stress absorption than C-E. The restorative material type changed the stress distribution of endocrown restorations. The fiber application did not affect the stress distribution in either endocrown group. But, more stress absorption was observed in fiber under IPS-E than C-E.
Asunto(s)
Resinas Compuestas , Litio , Cerámica , Coronas , Porcelana Dental , Análisis del Estrés Dental , Análisis de Elementos Finitos , Ensayo de MaterialesRESUMEN
Isolation or enrichment of biological molecules from complex biological samples is mostly a prerequisite in proteomics, genomics, and glycomics. Different techniques have been used to advance the efficiency of the purification of biological molecules. Bioaffinity chromatography is one of the most powerful technique that plays an important role in the isolation of target biological molecules by the specific interactions with ligands that are immobilized on different support materials. This review examines the recent developments in bioaffinity chromatography particularly over the past 5 years in the literature. Also properties of supports, immobilization techniques, types of binding agents, and methods used in bioaffinity chromatography applications are summarized.
Asunto(s)
Ácidos Borónicos/química , Cromatografía de Afinidad , Colorantes/química , Proteína Estafilocócica A/química , Adsorción , Animales , Humanos , Ligandos , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
Organosilicon monoliths carrying chromatographic ligands with different alkyl chain lengths were obtained by thiol-methacrylate photopolymerization. The use of thiol-ene chemistry in the presence of a main monomer with a series of methacrylate functionality (i.e., methacrylate substituted polyhedral oligomeric silsesquioxane) allowed the synthesis of organosilicon monoliths with high cross-linking density and carrying hydrophobic alkyl-chain ligands by a one-pot process. In the synthesis runs, 1-butanethiol, 1-octanethiol, and 1-octadecanethiol were used as the hydrophobic thiol ligands with the number of methylene units between 4 and 18. The selectivity analysis performed using cytosine/uracil retention ratio showed that alkanethiol-attached organosilicon monoliths exhibited hydrophobicity close to octadecyl-attached silica-based RP columns. In the RP, chromatographic runs performed in nano-liquid chromatography, phenols, alkylbenzenes, and PAHs were used as the analytes. Among the synthesized monoliths, retention-independent plate height behavior and the smallest plate heights were obtained with 1-octadecanethiol-attached organosilicon monolith for the analytes in a wide polarity range. With this monolith, the mobile phases prepared with ACN contents ranging between 35 and 85% v/v could be used for satisfactory separation of analytes in a wide polarity range.
Asunto(s)
Cromatografía de Fase Inversa/instrumentación , Cromatografía de Fase Inversa/métodos , Nanotecnología/instrumentación , Compuestos de Organosilicio/química , Compuestos de Sulfhidrilo/química , Interacciones Hidrofóbicas e Hidrofílicas , Metacrilatos/química , Procesos Fotoquímicos , Hidrocarburos Policíclicos Aromáticos/análisis , PolimerizacionRESUMEN
A hybrid monolith exhibiting almost retention independent separation performance in hydrophilic interaction chromatography (HILIC) was obtained by one-pot photoinitiated thiol-methacrylate polymerization. Polyhedral oligomeric silsesquioxane containing methacrylate units (POSS-MA) was used as the main monomer and crosslinking agent, together with a hydrophilic ligand with two carboxyl groups, mercaptosuccinic acid (MSA) as the thiol agent and chromatographic ligand. The isocratic separation of nucleosides, nucleotides and organic acids on MSA attached-poly(POSS-MA) monolith was investigated in HILIC mode. The van-Deemter plots for obtained for nucleosides, nucleotides and benzoic acids clearly showed that there were two regions in each graph with two different slopes in the studied range of linear flow rate (i.e. 0.2-4.3mm/s). The slope of plate height-linear velocity curve was so small in the low linear velocity region between 0.2-2.1mm/s while the slope in high linear velocity region between 2.1-4.3mm/s was so higher with respect to the first region. The van-Deemter plots sketched for all analyte grous used in HILIC mode obeyed this tendency Almost "retention independent plate height behavior" was demonstrated in HILIC, using nucleotides, nucleotides or benzoic acids as the analytes in the linear velocity range of 0.2-2.1mm/s. This behavior was explained by the porous structure of the synthesized monolith facilitating the convective transport of analytes. The variation of plate height was not retention-independent within high linear velocity range (>3.2mm/s) when nucleosides were separated in HILIC mode.
Asunto(s)
Técnicas de Química Analítica/métodos , Cromatografía Liquida , Metacrilatos/química , Polimerizacion , Siloxanos/química , Benzoatos/análisis , Interacciones Hidrofóbicas e Hidrofílicas , Nucleósidos/análisis , Nucleótidos/análisis , Compuestos de Organosilicio/química , Porosidad , Siloxanos/síntesis química , Compuestos de Sulfhidrilo/químicaRESUMEN
OBJECT: The center (axis) of rotation (COR) in the lumbar spine has been studied well. However, there is limited information on the kinetic and kinematic consequences of imposed shift in the location of the COR, although this type of shift can be seen after surgeries using motion preservation or dynamic stabilization devices. The objective of this study was to assess the kinetic and kinematic changes in the lumbar spinal segment due to various imposed CORs. METHODS: A 3D finite element model of the L4-5 segment was constructed and validated. The segment was loaded under a 7.5-Nm bending moment while constrained to rotate about various imposed CORs in the sagittal and axial motion planes. Range of motion, ligament forces, facet loads, and disc stresses were measured. RESULTS: The present model showed an agreement with previous in vitro and finite element studies under the same load and boundary conditions. Range of motion, facet forces, disc stresses, and ligament loads showed a strong association with the location of the COR. CONCLUSIONS: Acute alterations in the location of the COR can significantly change the load sharing characteristics within the spine segment. The normal location of the COR is a result of the tendency of the vertebra to move in the path of least cumulative resistance.
Asunto(s)
Vértebras Lumbares/diagnóstico por imagen , Vértebras Lumbares/fisiología , Rango del Movimiento Articular/fisiología , Tomografía Computarizada por Rayos X , Fenómenos Biomecánicos , Análisis de Elementos Finitos , Humanos , RotaciónRESUMEN
OBJECT: The goal of this study was to investigate the effect of ligament failure on the instantaneous center of rotation (ICR) in the lower lumbar spine. METHODS: A 3D finite element model of the L4-5 segment was obtained and validated. Ligament failure was simulated by reducing ligaments in a stepwise manner from posterior to anterior. A pure bending moment of 7.5 Nm was applied to the model in 3 anatomical planes for the purpose of validation, and a 6-Nm moment was applied to analyze the effect of ligament failure. For each loading case, ligament reduction step, and load increment, the range of motion of the segment and the ICR of the mobile (L-4) vertebra were calculated and characterized. RESULTS: The present model showed a consistent increase in the range of motion as the ligaments were removed, which was in agreement with the literature reporting the kinematics of the L4-5 segment. The shift in the location of the ICR was below 5 mm in the sagittal plane and 3 mm in both the axial and coronal planes. CONCLUSIONS: The location of the ICR changed in all planes of motion with the simulation of multiple ligament injury. The removal of the ligaments also changed the load sharing within the motion segment. The change in the center of rotation of the spine together with the change in the range of motion could have a diagnostic value, revealing more detailed information on the type of injury, the state of the ligaments, and load transfer and sharing characteristics of the segment.
Asunto(s)
Simulación por Computador , Análisis de Elementos Finitos , Ligamentos Articulares/fisiología , Vértebras Lumbares/fisiología , Modelos Anatómicos , Rango del Movimiento Articular/fisiología , Fenómenos Biomecánicos/fisiología , Humanos , Ligamentos Articulares/patología , RotaciónRESUMEN
Angiosarcoma is the most common primary cardiac malignancy with a poor prognosis. In this report, we describe a 28-year-old male patient presenting with symptoms and findings of myocardial ischaemia who has been finally diagnosed with cardiac angiosarcoma.