Video visualization profile analysis in online courses

In this article, student video visualization profiles are analyzed with two objectives: 1) to identify difficult sections in videos and 2) to predict student performance based on their video visualization profiles. For identifying critical sections in videos two novel indicators are proposed. The first one is designed to measure the complexity of the concept being described. The second proposal, identifies video sections that are more visually complex. For the first indicator, the average number of forward and backward passes are used. The higher the number of backward (forward) passes over a region, the more challenging (easy) the section is. For identifying sections with complex visuals, the number of pauses is recorded. Finally, the student performance prediction is carried out with the purpose of detecting the alignment between videos and their related questions. The results show that video visualization profiles are a good tool to identify video and question alignmen

Contrast sensitivity evaluation with filter contact lenses in patients with retinitis pigmentosa: a pilot study

Purpose: the aim of this pilot study was to test whether retinitis pigmentosa patients would benefit from filter contact lenses as an effective optical aid against glare and photophobia. Methods: fifteen subjects with retinitis pigmentosa were enrolled in this study. All of them were evaluated with filter soft contact lenses (MaxSight), filter glasses (CPF 527) and without filters (control). All patients were assessed for the three aid conditions by means of best corrected visual acuity (BCVA), contrast sensitivity (without glare and with central and peripheral glare)(CSV-1000) and a specific subjective questionnaire about quality of vision. Results: BCVA was slightly better with filters than without filter but the differences were not statistically significant. Contrast sensitivity without glare improved significantly with the contact lenses (p<0.05). The central glare had significant differences for the frequencies of 3 cpd and 18 cpd between the contact lens filter and the control group (p=0.021 and p=0.044, respectively). For the peripheral glare contrast sensitivity improved with contact lens versus control group for highest frequencies, 12 and 18 cpd (p<0.001 and p=0.045, respectively). According to the questionnaire the contact lens filter gave them more visual comfort than the glasses filter under the scenarios of indoors glare, outdoors activities and indoors comfort. Conclusion: the filter contact lenses seem to be a good option to improve the quality of vision of patients with retinitis pigmentosa

TNF-α/IL-1/NF-κB transduction pathway in human cancer prostate

TNFα exerts apoptosis throughout an intracellular transduction pathway that involves the kinase proteins TRAF-2 (integration point of apoptotic and survival signals), ASK1 (pro-apoptotic protein), MEK-4 (p38 activator and metastasis suppressor gene), JNK (stress mitogen activated protein kinase) and the transcription factor AP-1. TNFα also exerts proliferation by p38 activation, or when TRAF-2 simultaneously induces the transcription factor NF-κB by NIK. NIK and p38 may also be activated by IL-1. P38 activated several transcription factors such as Elk-1, ATF-2 and NF-κB. NIK also may activate NF-κB. The aim of the present article was to evaluate the different components of this TNFα/IL-1 transduction pathway in human prostate carcinoma (PC) in comparison with normal human prostate. In prostate cancer, pro-apoptotic TNFα/AP-1 pathway is probably inactivated by different factors such as p21 (at ASK-1 level) and bcl-2 (at JNK level), or diverted towards p38 or NIK activation. IL-1α enhances proliferation through IL-1RI that activates either NIK or p38 transduction pathway. P38 and NIK activate different transcription factors related with cell proliferation and survival such as ATF-2, Elk-1 or NF-κB. In order to search a possible target to cancer prostate treatment we proposed that inhibition of several proinflamatory cytokines such as IL-1 and TNFα might be a possible target for PC treatment, because decrease the activity of all transduction pathway members that activate transcription factors as NF-κB, Elk-1 or ATF-2.Ministerio de Educación y Cienci

Transporte de café cereza por cable aéreo de gravedad

Con el fin de determinar los parámetros que gobiernan el transporte de café cereza por cable aéreo de gravedad, se construyó en el Centro Nacional de Investigaciones del Café “CENICAFE”, un banco de pruebas con longitud de 38.5m y de altura variable, para simular diferentes condiciones topográficas. En el trabajo se determinaron las mejores combinaciones de flecha-pendiente que no requieran de ningún dispositivo de frenado de una carga de 60kg, en el punto de descarga. Para pendientes mayores del 15% se debe implementar un sistema de amortiguación o control de la velocidad de las cargas. Flechas mayores al 6% no son recomendables para el sistema de transporte de café cereza por cable aéreo de gravedad, debido a la presencia indeseable de una onda en el cable que distorsiona el descenso de las cargas. Teniendo en cuenta los valores de flecha-pendiente anotados anteriormente, el diámetro mínimo del cable de acero recomendado para transpotadores de gravedad, debe de ser “para longitudes de 300m, por cada 120m adicionales de longitud se debe aumentar el diámetro en 1/8 de pulgada. La capacidad de transporte de café cereza en el banco de pruebas, enviando cargas de 60kg, fue mayor a 5000 kg de café cereza por hora para las diferentes combinaciones de flecha-pendiente experimentadas

Graphic cryptography with pseudorandom bit generators and cellular automata

In this paper we propose a new graphic symmetrical cryptosystem in order to encrypt a colored image defined by pixels and by any number of colors. This cryptosystem is based on a reversible bidimensional cellular automaton and uses a pseudorandom bit generator. As the key of the cryptosystem is the seed of the pseudorandom bit generator, the latter has to be cryptographically secure. Moreover, the recovered image from the ciphered image has not loss of resolution and the ratio between the ciphered image and the original one, i.e., the factor expansion of the cryptosystem, is $1$.Peer reviewe

An analysis of safety evidence management with the Structured Assurance Case Metamodel

SACM (Structured Assurance Case Metamodel) it a standard for assurance case specification and exchange. It consists of an argumentation metamodel and an evidence metamodel for justifying that a system satisfies certain requirements. For assurance of safety-critical systems, SACM can be used to manage safety evidence and to specify safety cases. The standard is a promising initiative towards harmonizing and improving system assurance practices, but its suitability for safety evidence management needs to be further studied. To this end, this paper studies how SACM 1.1 supports this activity according to requirements from industry and from prior work. We have analysed the notion of evidence in SACM, its evidence lifecycle, the classes and associations of the evidence metamodel, and the link of this metamodel with the argumentation one. As a result, we have identified several improvement opportunities and extension possibilities in SACM

Clinical Performance of a New Hybrid Contact Lens for Keratoconus

OBJECTIVES: To compare the clinical performance of the Clearkone hybrid contact lens for the treatment of keratoconus against the habitual contact lens of the patients. METHODS: A total of 33 eyes from 18 patients were fitted with the Clearkone. High- and low-contrast visual acuity (HCVA and LCVA), central corneal thickness (CCT), and contrast sensitivity acuity (CSF) were recorded with habitual lenses (prestudy visit) and after 1 week, 15 days, and 1 month of wear of prescribed Clearkone. Subjective vision and comfort were rated using visual analogue scales (VAS). RESULTS: Three patients discontinued the study, one because of diffuse corneal staining after 1 day of use and the other two because of extreme discomfort. The rest of the patients completed the 1-month study. High contrast visual acuity and LCVA (logMAR) improved significantly from 0.16 ± 0.12 and 0.44 ± 0.22, respectively, with the patient's habitual contact lenses to -0.006 ± 0.058 and 0.23 ± 0.13 after 1 day wearing Clearkone, remaining significant during all follow-up visits (P<0.001; repeated measures analysis of variance [RM-ANOVA]). There were no statistically significant differences in the mean CCT. The improvement of CSF was statistically significant with hybrid contact lenses prescribed compared with the patient's habitual contact lenses (P<0.001; RM-ANOVA test). Improvement in VAS score, with prescribed Clearkone, was statistically significant for comfort (P=0.043; RM-ANOVA test), but not for the subjective vision (P=0.759; RM-ANOVA test). CONCLUSIONS: Clearkone provides an improvement in visual acuity, contrast sensitivity, and subjective comfort in patients with keratoconus when compared with other contact lens options. However, clinicians must get specific training to fit the lens and be aware of potential adverse events