bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical Features, Management Strategies, and Visual Acuity Outcomes of Candida Endophthalmitis Following Cataract Surgery
Authors: Gregori Ninel Z. , Flynn Harry W. , Miller Darlene , Scott Ingrid U. , Davis Janet L. , Murray Timothy G. , Williams Basil
Published: October 2019

BACKGROUND AND OBJECTIVE To report the clinical features, management, and visual outcome in patients with Candida endophthalmitis following cataract surgery. PATIENTS AND METHODS The Bascom Palmer Eye Institute Microbiology Laboratory database and corresponding medical records were reviewed from 1980 to 2006. RESULTS Five patients were identified. Endophthalmitis developed 7 to 60 days postoperatively (median, 14 days). Presenting visual acuity was 20/200 to counting fingers and final visual acuity was 20/25 to light perception. Whitish material was noted on the intraocular lens or lens capsule (4 of 5) or within the cataract wound (1 of 5). All patients received intravitreal amphotericin B and more than one pars plana vitrectomy procedure; four received systemic antifungal agents and four underwent intraocular lens removal. CONCLUSIONS Given whitish material on the intraocular lens, lens capsule, or cataract wound, Candida should be included in the differential diagnosis of early- or delayed-onset endophthalmitis following cataract surgery. Initial pars plana vitrectomy and intravitreal and oral antifungal medications may not achieve infection resolution. Intraocular lens explantation may assist in organism eradication. [Ophthalmic Surg Lasers Imaging 2007;38:378- 385.] AUTHORS From the Department of Ophthalmology (NZG, HWF, DM, JLD, TGM, BW), Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; and the Departments of Ophthalmology and Health Evaluation Sciences (IUS), Penn State College of Medicine, Hershey, Pennsylvania. Accepted for publication April 30, 2007. Supported in part by Research to Prevent Blindness, Inc., New York, New York. Address correspondence to Ninel Z. Gregori, MD, Bascom Palmer Eye Institute, 900 NW 17th Street, Miami, FL 33136.
Management of Persistent Glaucoma Secondary to Depot Methylprednisolone
Authors: Aydin Ali , Akin Tugrul , Bilge Ahmet Hamdi
Published: October 2019

This article describes two patients with recalcitrant ocular hypertension persisting 6 and 4 months, respectively, after periocular injection of methylprednisolone acetate despite maximum medical therapy. White sub-Tenon’s plaques of residual methylprednisolone acetate were excised surgically and analyzed for steroid activity using spectrophotometry. In both cases, intraocular pressure was normalized promptly after surgical removal of visible steroid. In both instances, biochemical analysis of the excised samples revealed residual steroid. Surgical removal of a residual methylprednisolone depot is an effective management choice in patients developing persistent intraocular pressure elevation after periocular injection. [Ophthalmic Surg Lasers Imaging 2007;38:399-401.] AUTHORS From Gulhane Military Medical Academy, Haydarpasa Training Hospital, Department of Ophthalmology, Istanbul,Turkey. Accepted for publication April 20, 2007. The authors thank the staff of the Biochemistry Service, Nalbantoglu State Hospital for providing essential support in this study. Address correspondence to Ali Aydin, MD, GATA Haydarpasa Egitim Hastanesi, Goz Hastaliklari Servisi, Tibbiye Caddesi, Uskudar, 34668, Istanbul, Turkey.
Limitation of 25-Gauge Vitrectomy Instrumentation in Highly Myopic Eyes
Authors: Singh Ajay , Fawzi Amani A. , Stewart Jay M.
Published: October 2019

In highly myopic eyes, a 25-gauge soft-tip needle is unable to remove fluid completely during air-fluid exchange because the needle is too short to reach the back of the elongated globe. In the simulated example, we found that the standard soft-tip cannulated needle is unsuitable for use in eyes with axial lengths greater than 31 mm. Other 25-gauge instruments are similarly unable to reach the back of a long eye. [Ophthalmic Surg Lasers Imaging 2007;38:437-438.] AUTHORS From the Department of Ophthalmology (AS, JMS), University of California, San Francisco, San Francisco; and the Doheny Retina Institute (AAF), University of Southern California, Los Angeles, California. Accepted for publication April 9, 2007. Supported by That Man May See, Inc., and an unrestricted grant from Research to Prevent Blindness, Inc., New York, New York. Dr. Singh is a Hearst Fellow. Address correspondence to Jay M. Stewart, MD, University of California, San Francisco, Department of Ophthalmology, 10 Koret Way, K301, San Francisco, CA 94143-0730.
Surgical Outcomes of Traditional Limbal-Based Versus Fornix-Based Trabeculectomy With Corneal Valve
Authors: Lin Yee-Pin Kristi , Zurakowski David , Ayyala Ramesh S.
Published: October 2019

BACKGROUND AND OBJECTIVE
To compare the safety and efficacy of fornix-based trabeculectomy with corneal valve to traditional limbal-based trabeculectomy with mitomycin C (MMC) in eyes with open-angle glaucoma.
PATIENTS AND METHODS
In this retrospective, nonrandomized, comparative study, 42 eyes that underwent
limbal-based trabeculectomy with MMC were compared with 32 eyes with fornix-based trabeculectomy
with corneal valve with MMC. Success was defined as final intraocular pressure (IOP) of at least 20% less than preoperative IOP and between 5 and 22 mm Hg
RESULTS
The preoperative and postoperative mean IOPs were 23.5 ± 12.2 and 11.5 ± 5.3 mm Hg, respectively, in the limbal-based group and 24.8 ± 11.1 and 11.7 ± 2.5 mm Hg, respectively, in the fornix-based group (P < .001 and P = .85, respectively). The fornix-based group had significantly less hypotony (3% vs 21%, P < .05).
CONCLUSIONS
Fornix-based corneal valve trabeculectomy with posterior placement of MMC sponges provides IOP control comparable to limbal-based traditional trabeculectomy, with decreased incidence of hypotony.
[Ophthalmic Surg Lasers Imaging 2007;38:471-477.]
AUTHORS
From the Department of Ophthalmology (Y-PKL, RSA), Tulane School of Medicine, Tulane University, New Orleans, Louisiana; and the Departments of Orthopaedic Surgery and Biostatistics (DZ), Children’s Hospital Boston and Harvard Medical School, Boston, Massachusetts.
Accepted for publication June 30, 2007.
Presented as a poster at the American Glaucoma Society annual meeting, Snowbird Resort, Utah, March 5, 2005, and the Association for Research in Vision and Ophthalmology annual meeting, Fort Lauderdale, Florida, May 1-5, 2005.
Supported in part by the Tulane Glaucoma Research Fund.
Address correspondence to Ramesh S. Ayyala, MD, FRCS, FRCOphth, Glaucoma Service, Department of Ophthalmology, Tulane University Medical Center, 1430 Tulane Avenue SL-69, New Orleans, LA 70112.
Optical Coherence Tomography Demonstration of Best’s Vitelliform Macular Dystrophy in a Child
Authors: Al-Kahtani Eman , Nowilaty Sawsan R.
Published: October 2019

Considering the importance of optical coherence tomography
in clinical decision making, the veracity of these images is critical. The authors describe a 5-year-old girl with Best’s vitelliform macular dystrophy of different stages of development in both eyes in which the optical coherence tomography appearance correlated
well with both the stages of the disease and the visual function. [Ophthalmic Surg Lasers Imaging 2007;38:511-513.]
AUTHORS
From the Department of Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh, Kingdom of Saudi Arabia.
Accepted for publication August 3, 2007.
Address correspondence to Eman Al-Kahtani, MD, Vitreoretinal Division, King Khaled Eye Specialist Hospital, P. O. Box 7191, Riyadh 11462, Kingdom
of Saudi Arabia.
Textural Properties of Choriocapillaris on OCTA in Healed Inflammatory Choriocapillaropathies
Authors: Khan Hashim Ali , Iqbal Fatima , Shahzad Muhammad Aamir , Khan Qaim Ali , Rashid Faisal , Sharjeel Muhammad , Khan Naeemullah , Pizzimenti Joseph
Published: October 2019

BACKGROUND AND OBJECTIVE:

To evaluate the flow characteristics and textural properties of choriocapillaris (CC) on optical coherence tomography angiography in eyes with resolved inflammatory choriocapillaropathies and Vogt-Koyanagi-Harada (VKH) disease.

PATIENTS AND METHODS:

A cohort of eyes with healed acute posterior multifocal placoid pigment epitheliopathy (APMPPE), serpiginous choroiditis (SC), and VKH disease were included. A 3 mm × 3 mm OCT angiogram of CC was acquired and graded for flow characteristics and textural properties.

RESULTS:

This study included 16 patients. Texture was heterogeneous in all eyes in the SC and VKH groups, and in four eyes (40%) in the APMPPE group. Most of the eyes with VKH disease had severe low flow, whereas most of the SC and APMPPE eyes demonstrated mild low flow. Heal duration had a strong negative correlation with severity of CC low flow and a weak, statistically nonsignificant correlation with texture heterogeneity.

CONCLUSION:

Despite the resolution of active inflammation, partial CC hypoperfusion and texture disruptions persist for longer durations and may resolve in a time dependent manner.

[
Ophthalmic Surg Lasers Imaging Retina
. 2019;50:566–572.]
Bilateral Release of Falciform Retrolental Adhesion by Scleral Buckling in Familial Exudative Vitreoretinopathy
Authors: Boss Joseph D. , Sonnie Christine , Sears Jonathan
Published: October 2019

Familial exudative vitreoretinopathy (FEVR) can often present with retinal falciform folds, and rarely with retrolenticular adhesive radial retinal folds. Management of advanced FEVR-associated tractional falciform folds with retrolenticular adhesion to the peripheral retina in the literature has been limited to vitrectomy with or without lensectomy. The authors describe a unique surgical management of a case of bilateral FEVR-associated tractional radial folds with nonaxial retrolenticular adhesion treated with scleral buckling with deferred laser, avoiding the complications associated with vitrectomy and lensectomy on ocular development.

[
Ophthalmic Surg Lasers Imaging Retina
. 2019;50:594–596.]
Neovascularized Best Disease in Child: Contribution of Optical Coherence Tomography Angiography
Authors: Elbany Sandra , Kodjikian Laurent , Boucher Sophie , Loria Olivier , Burillon Carole , Mathis Thibaud
Published: October 2019

Choroidal neovascularization (CNV) is a rare but severe complication in Best disease and autosomal recessive bestrophinopathy. However, the visualization of the neovascular membrane is difficult on fluorescein angiography (FA) and indocyanine green angiography (ICGA) because of dye leakage due to the accumulation of material. The authors' study reports a case series of pediatric Best disease where optical coherence tomography angiography (OCTA) contributed to the diagnosis of CNV and prompt treatment. Five eyes of three patients were included (two Best disease and one autosomal recessive bestrophinopathy). The mean age at diagnosis was 6.8 years ± 1.8 years (range: 5 years to 10 years). OCTA showed the typical “sea fan-shaped” neovascular membrane in all five eyes, whereas, in most cases, conventional imaging by FA and ICGA did not show clearly the neovascularization due to masking effect of the vitelliform material. OCTA seems to be a good alternative to diagnosing CNV in Best disease, especially in children, as it is a noninvasive, rapid technique for imaging, and does not require the administration of dyes.

[
Ophthalmic Surg Lasers Imaging Retina
. 2019;50:597–601.]
Motivation Path between the Difficulties and Attitudes of Using the E-Learning Systems in the Jordanian Universities: Aajloun University as a Case Study
Authors: Shakah Ghazi Hussein , Al-Oqaily Ali Taha , Alqudah Fadi
Published: October 2019

The E-learning systems are important for the universities due to the gained benefits from these systems. By using the E-learning system, the learning expenses can be reduced, the learning management would be improved, and the learning quality could be enhanced. Like any technology system, the students' motivation and positive attitude are success keys of the E-learning adoption by the universities. There are many difficulties faced by the students in using the E-learning system such as the technical difficulties, services difficulties, awareness, interactivity, and security concerns. This study aims to study the effects of the E-learning difficulties on the attitudes of using the E-learning systems through the path of students' motivation. The Technology Acceptance Model (TAM) is adopted to construct the conceptual model in this study. This study considered the E-learning difficulties as independent factor, the mediating factor is the motivation of using the E-learning systems, and the dependent factor is the attitudes toward the using of the E-learning systems. Based on the constructed model, three research hypotheses are developed to test the relationship between the E-learning difficulties and motivation, between motivation and attitudes, and between difficulties and attitudes through the motivation. The quantitative data method using questionnaire is used to collect the study data. The data collected from 154 students from Ajloun University as a case study of Jordanian universities. The case study is selected due the experience of the students in using E-learning system called BigBlueButton. The questionnaire data were analyzed using AMOS tool in order to discover the direct and indirect paths between the study variables. The significant results show that there moderator effects of the students motivation on the relationship between the E-learning difficulties and the attitudes toward the using of these systems. The P-values is significant at p < 0.05 on the relationship between the study variables. Another important result is that the difficulties of E-learning such as technical, services, and interactivity should be avoided to improve the motivation level of using the E-learning systems. Also, the low motivation level lead to decrease the attitudes level toward the using of E-learning systems. The contribution of this study represented by fill the research gap of the motivation path on the relationship between the E-learning difficulties and attitudes. This study gives the university important details about the features of success implementations of E-learning systems.
The Competitiveness of Master of Education Graduates: Porter’s Diamond Analysis
Authors: Sukardi Sukardi , Rusdiawan Rusdiawan , Wardana Lalu Ali
Published: October 2019

The competitiveness of university graduates is largely determined by its capacity to create and maintain competitive advantage. Based on the Porters' Diamond model, this study measures the competitive advantage of universities in Indonesia, especially the master's level of education. This model has almost never been in educational institutions, except for economic / business sectors. The data were collected through a survey and interpreted by the Porters' Diamond Compatibility Analysis. The competitiveness of master of education graduates in Indonesia is already in good level but is still considered low in the Southeast Asian level. Four factors of Porters' Diamond competitiveness have low supporting capacity so that it leads to the less competitiveness of the graduates. Strengthening the supporting capacity of demand conditions, educational relevance, and educational strategies are then becoming top priorities, including strengthening specific skills and developing sector-based competency.
Rezensionen
Authors: Haldimann Andreas , Leuenberger Chr.
Published: October 2019

Rezensionen zu:
Dirk W. Hoffmann:
Forcing – Eine Einführung in die Mathematik der Unabhangigkeitsbeweise
. 432 Seiten, 34.90e (Hardcover). Books on Demand, 2018; ISBN 978-3-746-04460-6,
von Andreas Haldimann;
und zu:
J. Stillwell:
Elements of Mathematics.
From Euclid to Gödel. 422 Seiten, $ 40.00 (Hardback). Princeton University Press, Princeton and Oxford, 2016; ISBN 978-069117168-5
von Chr. Leuenberger.
O papel da formulação de questões durante a leitura compartilhada de livros na educação infantil
Authors: Pereira Aline E. , Gabriel Rosângela , Justice Laura M.
Published: October 2019

The shared reading of books is one of the activities that most contributes to the development of young children's  language  (JUSTICE; SOFKA, 2010; SÉNÉCHAL, 2015; EVANS; SAINT-AUBIN, 2005; SÉNÉCHAL; LEFEVRE, 2002) and has effects in the acquisition of the written language registers (BUS et al., 1995). However, the effects of this contribution depend on how the adult interacts and encourages the child's participation in the discussion and reflection beyond the text. Young children who actively participate in adult-led shared reading of books, which interact with them through questions, word-labeling, and referents, have greater gains in vocabulary than children who passively hear the book reading (SÉNÉCHAL et al., 1995). In addition, the use of questions plays a key role in directing attention and maintaining the child's participation in the activity of shared reading. The purpose of this study is to (1) determine how often preschool teachers ask questions during shared reading of books with their students, and (2) identify the types of questions that teachers asked related to basic vs. complex questions. A total of nine teachers and their students aged 3 to 5 years, from a city in the interior of Rio Grande do Sul, Brazil, participated in the study. Two shared reading sessions of each teacher (n = 18) were recorded on video, transcribed and coded using an adapted version of the Systematic Assessment of Book Reading-Transcript Coding Version 2.1 (ZUCKER et al., 2017). The results show that during the eighteen shared reading sessions, teachers compiled a total of 329 questions, classified into two categories: basic questions and complex questions. From the total, the basic ones had a higher frequency (n = 285) and complex questions were formulated less frequently (n = 44). The results of this research are in line with other studies (PENTIMONTI et al., 2018; BECK; MCKEOWN, 2001; GIROLAMETTO et al., 2000) that show that teachers usually ask basic questions more frequently when compared to complex questions. Therefore, we emphasize the importance of call  teachers attention to the value of shared reading, mediated by an interaction that favors the formulation of questions, seeking to expand the proportion of complex questions, given the influence that this type of activity has on the cognitive and linguistic development of children.
Um estudo sobre o acento gráfico na aquisição da escrita: ortografia e fonologia
Authors: Ney Luanda Alvariza Gomes , Miranda Ana Ruth Moresco
Published: October 2019

This paper discusses the criteria used by third and fifth graders who attend a public school, in Pelotas, RS, Brazil, regarding the function of diacritical marks in the writing system. Considering the close relationship between prosodic stress and the rules of use of diacritical marks, the study reported in this paper aimed at investigating children's hypotheses concerningthese orthographic devices. Data were collected by a controlled writing instrument, which was especially designed for this research, and by clinical interviews guided by the Piagetian method (Carraher, 1989). After completing awriting task, children were induced to explain the reasons that led them to usediacritics in their spelling. The analysis of data on their written production showed that children got the diacritical mark right, mainly in contexts in which alternation of vowel timbre could occur, that is, in medium and low medium vowels. Results of the interviews highlighted the emergence of criteria based on acoustic and graphic aspects. The analysis allowed us to define a hierarchy of acoustic criteria, i. e., vocalic timbre, vowel duration and prominence.
Políticas públicas de alfabetização
Authors: Scliar-Cabral Leonor
Published: October 2019

In the 2016 National Early Literacy Assessment (ANA) (INEP, 2017), 2,160,601 students from Brazilian public schools were evaluated at the end of the 3rd year of the Early Literacy Cycle, in reading and writing, among which only 12.99% reached the aimed level (4) in reading and only 8.28% reached the aimed level (5) in writing. However, in Lagarto city (Sergipe State), which, according to the aforementioned evaluation, had ranked last in Brazil, with only 3.02% of students at the aimed level in reading, and penultimate place in writing, with only 1.84%, things became quite different. Being taught by Scliar Early Literacy System, seventy children were reading with fluency and comprehension and, above all, with pleasure, by the end of the first year, in 2017. I analyze two documents on early literacy public policies: The final version of the Common National Curricular Base (BRAZIL, MEC 2017) and the decree 9.765 of April 11, 2019, which establishes the National Literacy Policy and Iexplain why the lack of knowledge about advances in sciences such as linguistics, psycholinguistics, neuropsychology and neuroscience leads to failure in early literacy.
Psicolinguística do bilinguismo: implicações em processos formais de aquisição de línguas
Authors: Ortiz Preuss Elena Ortiz
Published: October 2019

In this article we discuss the interrelationships between contextual and individual variables in the acquisition and use of L2, based on researches developed by our team. We assume that in the late acquisition of L2 there is variability in the proficiency of the learners, and that it is necessary to (re)know the effects of the individual variables in the teaching-learning processes. The experiments, which were created according to the Psycholinguistics of bilingualism and carried out in formal contexts of acquisition, evaluated associations between attention and working memory systems and the performance of bilinguals in their L2. The results, although incipient, indicate that effects of pedagogical approaches can be affected by individual differences. In addition, they reveal the need of more experiments that focus these variables on L2 teaching-learning processes.
Leitura em voz alta: variação linguística e o sucesso na aprendizagem inicial da leitura
Authors: Freitag Raquel Meister Ko , Sá José Júnior De Santana
Published: October 2019

In an interface between psycholinguistics and sociolinguistics, considering stylistic monitoring (speech à oral activities à reading aloud) and the necessary conditions for early literacy, this paper presents the reading profiles of 3rd grade students from elementary school and relates them to performance on a reading comprehension test and to the occurrence of variable features of speech in reading aloud. The results show that the reading aloud which presents variable features of speech cannot be considered “inaccurate”; instead, these features occurred only in proficient and word-to-word types of reading, and only by students who reached higher levels on the test.
The effects of cognitive training on executive functions and reading in typically-developing children with varied socioeconomic status in Brazil
Authors: Weissheimer Janaina , Fujii Renata Callipo , Souza Juliana Geizy Marques
Published: October 2019

Recent findings show that children from low-socioeconomic status (SES) tend to have reduced performance on several tasks involving working memory, attention and executive control.  In addition, researchers argue for the effectiveness of training of these same cognitive skills as a way to ameliorate children’s EF skills as well as scholastic outcomes. To investigate possible training effects and to study the impact of SES on scholastic achievement in Brazilian children, we trained 61 children for 5-7 weeks and compared their performance with that of 60 age-matched peers on measures of executive functions and reading. Our results demonstrate a general effect of SES for the dependent variables. Furthermore, our findings demonstrate a positive near transfer effect on a working memory and a selective attention test and a far transfer effect on the words and pseudowords reading measure.
Território e participação: Lévy-Bruhl nos país dos Karajá
Authors: Nunes Eduardo Soares
Published: October 2019

O objetivo deste artigo é tentar extrair da obra de Lucien Lévy-Bruhl, um conceito de “território” produtivo do ponto de vista do atual estado da literatura etnológica; extraí-lo e, em um segundo movimento, experimentá-lo a partir do material etnográfico Karajá. Depois de explorar brevemente alguns dos aspectos centrais da obra o autor francês, sobretudo sua noção de participação, passo a elaborar o conceito karajá de hãwa, geralmente traduzido pelos índios por “território”, como um “amontoado de participações e exclusões”, segundo o entendimento de Lévy-Bruhl. Pois um hãwa associado a uma aldeia engloba vários territórios heterogêneos habitados por seres Outros, entre os quais o que há não é uma divisão extensiva, mas uma superposição intensiva. Habitar um hãwa, portanto, demanda uma vívida percepção dos modos de relação que esse “amontoado” implica, bem como de uma avaliação cuidadosa das consequências, ou os efeitos, dessas suas ações – uma cosmopolítica do respeito.
Mundo quase árido
Authors: Medeiros Rondinelly Gomes
Published: October 2019

Neste ensaio percorremos as formas sob as quais os processos colonizadores tomaram o sertão semiárido brasileiro de assalto, desde a invasão armada do século XVII até os recentes empreendimentos industriais, apontando alguns de seus desdobramentos político-epistêmicos e pressupostos estético-ontológicos. Nossa intenção é mostrar que o semiárido é transformado em uma wasteland de forma a se propagar a ideia de que o Nordeste brasileiro precisa ser salvo de si mesmo. Entretanto, os multiformes modos de vida que re-existem por baixo, por dentro e contra o processo de colonização são exemplos de resistência criativa e cosmopolíticas.
Local Elections and Organised Crime: The Case of Michoacán, Mexico
Authors: Ochoa Jerjes Aguirre , Herrera Torres Hugo Amador
Published: October 2019

This study, based on ethnographic analysis, reveals that municipal government elections in Mexico have become spaces of struggle among criminal groups striving to strengthen their presence throughout the territory. In municipal contexts characterised by institutional vacuums, delinquent organisations have succeeded in capturing political spaces. We argue that the continuous violence that has plagued the country since 2013 can be explained largely by factors of an institutional order coupled with distorted electoral processes in municipalities and states, exacerbated by widespread citizen disenchantment with democracy and especially manifest at the level of local government. This situation suggests the need for strategies that address the influence of these criminal groups that go beyond police-based approaches and for actions designed to improve the quality of state institutions.
A Phonological, Morpho-Syntactical Study of Nominal Compounding in Japanese
Authors: Li Wenchao
Published: October 2019

This paper provides a distributed-morphological analysis of nominal compounding in Japanese in an effort to pin down the phonological, morphosyntactic mechanism in nominal compounding. The findings reveal that the semantic relation between the N1and N2 has seven variations: Object + Tran.conj.; Instrument + Tran.conj.; Modifier - Tran.conj.; Place - Tran.conj.; Method - Tran.conj.; Cause - Tran.conj.; and Subject –tran. conj..Among the variations, sequential voicing is only subject to [Nobject - N TRAN.conj.] nominal compounds. Moreover, during the process of forming a nominal compound, the second constituents (N2) rendered by aspirate consonants /k/ and /t/ are very likely to receive sequential voicing. When the N2 is conveyed by consonant /c/ and fricative consonant /h/, sequential voicing does not occur. Syntactically, Japanese nominal compounds are all right-headed. The formation process of all nominal compounds is a matter of ‘word derivation’ given the fact that, (i) √Root and the latter added morphemes are not semantically associated and it is after the merger that the semantic interpretation is established, and (ii) the N-N’s category is determined by the added morphemes. In addition, lexicalisation plays an essential role during the nominal compounding process. Crucially, lexicalisation only applies to the[Nobject - N TRAN.conj.] type of compound.
Absorción de radiación en átomos y su aplicación en la experimentación
Authors: Mejía Castellanos Roberto Enrique
Published: October 2019

Este artı́culo muestra un breve desarrollo de la exposición de los átomos a ondas electromagnéticas y como los resultados son aplicables dentro de la experimentación a determinación de constantes como la razón h̄/m donde m es la masa atómica del elemento utilizado; asi como la constante de estructura fina α, con alta precisión. Preliminarmente se hace el tratamiento teórico correspondiente utilizando la teoria de perturbación dependiente del tiempo ya que la configuración experimental utiliza interferometria atómica con pares de pulsos π/2, esto permite estados deseados en los átomos; posteriormente se efectua el análisis experimental exponiendo un desarrollo de la interferómetria atómica utilizando diferentes configuraciones y mostrando resultados obtenidos en experimentos previos.
Ecuaciones de transporte para un gas diluido
Authors: Ordóñez Martínez Cristian Joel
Published: October 2019

Se pretende detallar la teorı́a fundamental de la fı́sica estadı́stica clásica, desde la idea del por que es necesario estas herramientas matemáticas para entender acerca de la dinámica de gases diluidos, se demuestra de manera alternativa el teorema de Liouville, lo cual nos es importante para poder definir la distribución de probabilidad (ensamble), para después encontrar la ecuación de Boltzmann, tomando en cuenta los encuentros moleculares, la cual nos da las soluciones acerca de los parámetros, al saber, transporte de momento, transporte de masa y transporte de energı́a en conjunto con el teorema de Gibbs.
Niveles de intensidad de instrumentos musicales
Authors: Reyes Alonzo José Lisandro
Published: October 2019

Al escuchar diferentes instrumentos musicales se logra apreciar que algunos son bastante sonoros y los de viento de los que se oyen más fuerte. En esta investigación se estuvo midiendo los niveles de intensidad de algunos instrumentos musicales para conocer sus niveles de intensidad utilizando un sonómetro digital. Posteriormente se estuvo midiendo el nivel de intensidad en el corredor central en el edificio donde está ubicado el Departamento de Arte y conocer que tan apropiado o no es el local para que los estudiantes de la carrera logren sus estudios. El proyecto fue realizado con la colaboración de estudiantes de la carrera de Medicina y matriculados en la clase de Biofı́sica. Los estudiantes realizaron una continua medición de 8:00 a 16:00 y los resultados nos muestran la necesidad de mejorar esas instalaciones que garanticen el éxito de sus estudiantes.
Funciones de Bessel y Neumann
Authors: Ávila Salvador , Trigueros Óscar , Chinchilla Roberto
Published: October 2019

En este trabajo, trataremos la función Bessel generalizada, que es la solución a la ecuación diferencial de Bessel de segundo orden , originándose del desarrollo de la ecuación de Laplace y la ecuación de Helmholtz en coordenadas cilíndricas y esféricas. Iniciaremos con la función de Bessel de primera clase solución linealmente independiente de la ecuación diferencial de Bessel, usando principios de simetría y condiciones de convergencia, para demostrar su valides. Veremos también las funciones de Bessel de segunda y tercera clase, denominadas respectivamente función de Neumann y la función de Hankel. Las funciones Bessel tienen diversas aplicaciones, como en: ondas electromagnéticas en guías de onda, conducción de calor en objetos cilíndricos, difusión en una red, entre muchas otras.
Introducción al análisis y diseño de antenas
Authors: López Jonnathan , Díaz Ingrid , Sevilla Abdiel
Published: October 2019

Las antenas son estructuras diseñadas para radiar energía electromagnética de una manera eficiente y pre-establecida mediante el diseño. Sin una antena eficiente, la energía estaría localizada y la transmisión de energía inalámbrica no sería posible. En este trabajo se describe de forma introductoria el fenómeno de radiación para luego abordar teoría básica de antenas, incluyendo la caracterización de éstas mediante una serie de parámetros. Para ello se introduce la notación fasorial de campos de manera conveniente. Además, se hace referencia al contexto histórico y el papel que han desempeñado estos dispositivos en las últimas décadas. Por último, se incluyen códigos desarrollados en Matlab con el fin de exponer las capacidades de software computacionales actuales para el análisis y diseño de antenas.
Experimentos Clásicos en Espectroscopı́a de Gases Desarrollados en la Carrera de Fı́sica de la UNAH
Authors: Malaverth Edwin Fernando , Alcerro Luis , Coto Mario , Mejía Roberto
Published: October 2019

El presente artı́culo expone el desarrollo, análisis y resultados de una serie de dos experimentos clásicos que exponen en evidencia la teorı́a de Bohr (1913) sobre los espectros de emisión caracteristicos de los elementos, además de la cuantización en los estados atómicos de los electrónes. El experimento se llevó a cabo en la escuela de Fı́sica de la UNAH-CU mediante dos métodos diferentes y estuvó bajo el asesoramiento del Lic. Roberto Mejı́a. En primer lugar se efectuó la calibración de un espectroscopio Kirchhoff-Bunsen para posteriormente confirmar las energı́as de los fotones en el espectro de emisión del de Hidrógeno, Luego se configuró y calibró un espectroscópio basado en el principio de difracción de las componentes espectrales de emisión, confirmando nuevamente el espectro de emisión del hidrógeno. A través del análisis y procesamiento de los datos experimentales se logra tambien mostrar en evidencia el planteamiento de Balmer (1885).
Tres métodos de espectroscopía de gases para la obtención de espectros de emisión y la medición de la constante de Rydberg
Authors: Mejía Roberto , Hernández Jocsan
Published: October 2019

El presente artículo pretende exponer tres métodos en espectroscopia de gases para obtener las longitudes de onda en el espectro discreto de emisión del hidrogeno con una precisión que oscila entre 0.19% y 0.95 %, y una exactitud entre 4.6% y 0.45 %; en los dos primeros métodos se utilizan como referencia líneas definidas para dos gases nobles y vapor de mercurio, lo que permite una calibración adecuada para un espectrómetro Kirchhoff-Bunsen y una configuración utilizando una réplica de difracción de 500 líneas/mm analizando un primer patrón de difracción no simétrico. El tercer método utiliza la teoría de difracción de ondas para determinar la longitud de onda de cada línea espectral de emisión observada en un patrón simétrico de primer orden. Posteriormente se verifica la validez del método más exacto y preciso llevando a cabo la medición de la constante de Rydberg para tres líneas de emisión en el hidrogeno con una precisión del 0.34 %
Evaluación de un arreglo de diodos en 2 dimensiones para dosimetría física y clínica de rutina en haces de electrones en radioterapia
Authors: Sánchez-Lovell María José , Rojas Campos Isaac
Published: October 2019

En este estudio, se tiene la intención de mostrar la factibilidad de utilizar un arreglo de diodos bidimensional para dosimetría de electrones. Se calibró el arreglo con energías de 9, 12 y 16 MeV. Se evaluaron la dosis en eje central, planicidad, simetría, reproducibilidad a corto plazo, contra mediciones con cámara de ionización plano-paralela y se realizó gamma análisis para la comparación de mapas de fluencias exportadas y medidas. En reproducibilidad a corto plazo se obtuvieron coeficientes de variación menores al 1.0% para todas las energías. Para planicidad y simetría se obtuvieron diferencias absolutas menores a 3.0 %. En el gamma análisis, los porcentajes de los puntos de datos del arreglo de diodos que concordaron con la dosis planificada fueron: 90.8 a 97.9% para 9 MeV, de 52.7 a 81.7% para 12 MeV y de 69.2 a 94.2% para 16 MeV. Las diferencias en dosis absoluta entre el plan y la medición con Mapcheck fueron menores al 2.0 %, excepto para la energía de 12 MeV (3.2 %). La concordancia entre los datos obtenidos con cámara de ionización y el arreglo de diodos respaldan el uso del Mapcheck como un método confiable para dosimetría de electrones
Análisis estratigráfico de una zona con alto riesgo al deslizamiento por medio de métodos de prospección geofísica
Authors: Vargas Luis E.
Published: October 2019

En este trabajo se presenta el estudio realizado en una zona con alto riesgo al deslizamiento, ubicada en el Barrio Campo Cielo del municipio de Comayagüela, Francisco Morazán, Honduras; en el periodo de Febrero de 2013. Dicho estudio se realizó haciendo uso de los Métodos de Prospección Geofísica de Refracción Sísmica, y Resistividad Eléctrica. En este caso en particular, se seleccionó como método primordial el Método de Refracción Sísmica debido a la finalidad del estudio que fue analizar la estructura estratigráfica del lugar, en búsqueda de zonas de susceptibilidad a deslizamientos que puedan existir. Con los datos de ´este estudio, mediante la comparación de dos métodos aplicados, fue posible determinar zonas de susceptibilidad a deslizamiento que tiene la zona aun, así como valores estimados del espesor de la capa de sedimento suelto que posee la zona; estimada en seis (6) metros en las cercanías de la corona del deslizamiento y de diez (10) metros en la base del deslizamiento.
Electromagnétismo en varias dimensiones
Authors: Velásquez Angel , Herrera Jhony A.
Published: October 2019

En este artículo se obtendrán expresiones para la densidad de carga, el campo eléctrico, el potencial escalar y la densidad de corriente eléctrica en más dimensiones, utilizando el formalismo de teoría de cuerdas, el cual ha tenido mucha aceptación por los científicos en los últimos años.
Cálculo del segundo coeficiente del virial con el potencial de Lennard-Jones
Authors: Reyes Marco Antonio , Galo Roldán Alejandro
Published: October 2019

En este trabajo se calcula el segundo coeficiente del virial usando el enfoque clásico ya que el Argón que es el gas seleccionado tiene una longitud de onda térmica menor que el diámetro de colisión así el efecto cuántico es despreciable. El potencial utilizado para calcular el segundo coeficiente del virial es el potencial de Lennard-Jones, los resultados obtenidos se comparan con los coeficientes experimentales reportados en la literatura científica, los resultados teóricos son muy parecidos a los experimentales de hecho están dentro del error experimental. Se calcularon ecuaciones para el segundo coeficiente utilizando mínimos cuadrados, ya que mediante estas ecuaciones se pueden calcular propiedades termodinámicas de interés. Finalmente se calculan algunas propiedades críticas utilizando el segundo coeficiente del virial.
Curvatura de la Luz
Authors: Sánchez Villanueva Javier
Published: October 2019

La idea de que la luz se curva cuando pasa cerca de un cuerpo masivo es vieja, se remonta al menos a Newton y Laplace. En un modelo corpuscular de la luz, tal como el de Newton, es natural que la atracción gravitacional hará que una lı́nea recta de luz se curve como la trayectoria de cualquier cuerpo de materia. El doblamiento gravitacional de la luz debido al sol vista en la teorı́a de Newton para un fotón masivo, tomando que la masa tiende a cero, resulta ser 0.87 arcosegundos - exactamente la mitad del valor predicho por la teorı́a general de la relatividad. Cuando Eddington midió el valor correcto durante un eclipse solar observado en la isla del prı́ncipe en 1919, obtuvo un resultado en acuerdo con la teorı́a de Einstein, donde la predicción de Newton fue de un factor de 2 demasiado pequeño. Fue este suceso (”Newton se equivocó - Einstein tuvo razón”) que trajo fama a Einstein. Hoy el valor relativı́stico del ángulo deflectado se ha provado correctamente en varias observaciones a un valor exacto.
Aplicación de Modelos Matemáticos para el Estudio de Fuerzas de Casimir
Authors: Pinto Jacinto Daniel , Galo Roldan Alejandro
Published: October 2019

Los fenómenos fı́sicos conocidos frecuentemente como Efecto Casimir tienen naturaleza cuántica, estos fenómenos se asocian a la existencia de oscilaciones de vacı́o de campos cuánticos. Este fenómeno surge debido a que la energı́a del estado de vacı́o sufre una distorsión debida a la presencia de contornos.
Método de Numerov para el Cálculo de Niveles de Energía de la Molécula de Hidrógeno
Authors: López Zavala Edsson Ricardo , Galo Roldán Alejandro
Published: October 2019

Con anterioridad hemos estudiado sistemas de dos cuerpos como el átomo de hidrogeno y se han estudiado sus soluciones de manera satisfactoria, podemos expandir este estudio a problemas más complejos como ser el de los átomos hidrogenoides o también átomos polielectrónicos, pero aún más interesante es ver un problema aún más general que es el de las moléculas que resultan ser problemas muy complejos para los cuales nos apoyaremos en métodos numéricos para resolverlos. En este trabajo usaremos el método de Numerov para cumplir esta tarea.
Determinación de la Relación de Dispersión de un Cristal Unidimensional con el Modelo de Kronig Penney Utilizando Funciones de Green
Authors: Domínguez Villanueva Luis Alonso , Galo Roldán Alejandro
Published: October 2019

Las funciones de Green es aplicada para describir aspectos cualitativos generales de la estructura de bandas para el modelo Kronig Penney, al mismo tiempo se plantea la ecuación de Lippmann-Shwinger como forma alterna de la ecuación de Schrödinger para la resolución de este problema particular y su solución en una dimensión para potenciales periódicos modelados por deltas de Dirac, deduciendo de esta forma la relación de dispersión.
La Física de los Viajes en el Tiempo a través de un Agujero de Gusano
Authors: Isea Raúl
Published: October 2019

El presente trabajo nos introduce en la física de los viajes en el tiempo empleando para ello los agujeros de gusano. Se resalta como la cinematografía nos sumerge en posibles paradojas o contradicciones temporales, pero que se pueden reinterpretar bajo el principio de auto consistencia de Nóvikov, que explica que son solo posibles aquellos eventos que no logran cambiar el futuro. Por otra parte, se desarrolla un ejercicio mental con una bola de billar que viaja al pasado cuando atraviesa un agujero de gusano para que posteriormente colisione consigo misma, claro símil de la paradoja de los abuelos. Así mismo, se analizan los agujeros de gusano desde la óptica de la relatividad general, y como se vinculan con la teoría de campo de Einstein.
Análisis de esfuerzo máximo de compresión y flexión de tres tipos de cementos refractarios utilizados en calderas
Authors: Romero Reyes Karla María , Irías Caballero Carlos Francisco , Sánchez Cárcamo Carlos José , Rummel Gerhard
Published: October 2019

La selección adecuada de cementos refractarios utilizados en calderas y hornos industriales, depende de los criterios de calidad, mejoramiento y verificación de las propiedades mecánicas, térmicas y químicas. Nuestro trabajo se basa en la obtención de las propiedades mecánicas de flexión (MOR, Modulus Of Rupture) y de compresión (CCS, Cold Crushing Strength) realizadas a temperatura ambiente para tres tipos de cementos refractarios.
Problema de dos cuerpos sometidos a varios tipos de fuerzas centrales
Authors: Alcerro Luis
Published: October 2019

El problema de dos cuerpos sometidos a una fuerza central es uno de los modelos más importantes de la mecánica clásica debido a que muchos sistemas físicos se modelan de manera similar.En el presente trabajo se desarrolla este problema, obteniendo las órbitas de Kepler, órbitas debido a una fuerza proporcional al inverso del cubo de la distancia, y se finaliza con la introducción de un potencial tipo Yukawa en la ecuación de órbitas clásica.
Solución Numérica por Python de la Relación de Dispersión para un Cristal Unidimensional con el Modelo Kronig Penney
Authors: Domínguez Villanueva Luis Alonso , Galo Roldán Alejandro
Published: October 2019

En este artı́culo se presentará un método numérico junto con la programación de un script para calcular soluciones de la relación de dispersión del modelo Kronig-Penney como una continuación del trabajo presentado con las funciones de Green y la relación de dispersión. Se utilizará los paquetes básicos del programa Python sin utilizar las funciones de análisis numérico existentes en python. Al mismo tiempo se calculará las bandas de energı́a permitidas en función del vector de onda representando los resultados mediante una interfaz gráfica.
Implementación de Práctica Experimental de Laboratorio del Decaimiento Radiactivo del Estroncio-90 para el Área de la Salud
Authors: Álvarez Herson , Coto Mario
Published: October 2019

El presente artı́culo expone el desarrollo de una practica experimental de laboratorio de decaimientos radiactivos, utilizando Estroncio-90, este experimento se presenta como parte del contenido de la asignatura de Biofı́sica para los estudiantes de la carrera de medicina en el área de Fı́sica Moderna. El experimento se divide en dos partes fundamentales, que son el calculo de la constante de decaimiento (λ) y la realización de la gráfica de decaimiento de los conteos por segundo versus el tiempo transcurrido, para realizar dicha practica se hará uso de un medidor SPECTRUM TECHNIQUES ST-160 que proporcionará los conteos por segundo de la muestra radiactiva, en este caso Estroncio-90. El uso de radio isotopos es de mucha importancia actualmente en la medicina como agentes terapéuticos y de diagnostico, por tal razón la importancia de realizar este tipo de experimentos para que los estudiantes entiendan y se familiaricen con estos fenómenos fı́sicos.
Estabilidad orbital de planetas no coplanares en un sistema estelar binario
Authors: Henríquez Raúl A.
Published: October 2019

Recientemente se ha sugerido la búsqueda de planetas que orbitan alrededor de un sistema estelar binario (sistemas circumbinarios) con planos orbitales muy inclinados relativo al plano orbital del sistema binario. Si las órbitas de estos planetas son estables, la mayoría de los planetas circumbinarios podrían ser de este tipo. En este trabajo, se han estudiado las estabilidades de órbitas de planetas circumbinarios con una inclinación ipl = 60°, relativo a la órbita del sistema binario. Para ello se utilizó un código de integración de N cuerpos, haciendo simulaciones de un sistema circumbinario en particular: un planeta de masa mpl = 10−5 M☉ y dos estrellas de masas m1 = m2 = 0.5 M☉. Se hicieron 1174 simulaciones numéricas de las órbitas del planeta circumbinario, variando la distancia relativa (κ) entre la órbita del sistema binario y la órbita del planeta, encontrándose la órbita crítica κcrit = 1.955 y algunas resonancias de la órbita del planeta, en las que se observaron inestabilidades o cambios grandes en la excentricidad del planeta.
Trasformada rápida de Fourier utilizando Python
Authors: Spilsbury Michael , Euceda Armando
Published: October 2019

A continuación se presenta un programa de computadora para calcular la transformada discreta de Fourier utilizando el algoritmo de la transformada rápida de Fourier (FFT por sus siglas en ingles). Desde 1965, cuando James W. Cooley y John W. Tukey publicaron dicho algoritmo, su uso se ha expandido rápidamente y las computadoras personales han impulsado una explosión de aplicaciones adicionales de la FFT. Como lenguaje de programación se usara Python, que es un lenguaje de programación multiparadigma, esto significa que más que forzar a los programadores a adoptar un estilo particular de programación, permite varios estilos: programación orientada a objetos, imperativa y funcional. Los usuarios de Python se refieren a menudo a la filosofía Python que es bastante análoga a la filosofía de Unix. Al mismo tiempo se integrará un módulo de Fortran para mejorar el desempeño.