Measuring Thickness and Pretilt in Reflective Vertically Aligned Nematic Liquid Crystal Displays

Pretilt angle is a parameter of the utmost importance in the ultimate performance of vertically-aligned negative nematic LC displays. When these devices work in reflective mode, as is the LCOS microdisplays, accurate measurement of pretilt angles becomes a difficult problem, since usual experimental setups based on retardation of the polarization components of the impinging light are proportional to the product effective birefringence (neff - no) times thickness, and any attempt to separate these variables is cancelled out by symmetry. This work shows a relatively simple method capable of separating both variables. An experimental setup specifically aimed at vertically aligned reflective cells has been prepared. At the same time, a simulation model has been developed taking into account the properties of actual reflective displays. Comparison between experimental and theoretical results shows some discrepancies that can be explained assuming that the LC profile contains a residual twist. Including that twist in the model, an excellent agreement between theory and experiment has been achieved. Matching of simulations and measurements yields to the separate determination of pretilt angle and thickness and gives good estimates for the residual twist angle

Predictors of Creativity in Young People: Using Frequentist and Bayesian Approaches in Estimating the Importance of Individual and Contextual Factors

© 2020 American Psychological Association. The development of creativity in young children has been studied extensively, but relatively few studies have examined the period of adolescence and emerging adulthood in relation to creative potential. The present study uses a combination of frequentist and Bayesian analyses to evaluate the impact of individual factors (e.g., IQ) and contextual factors (e.g., pursuit of creative hobbies) on creative ideation in three cohorts of young people aged 14-20 years. Measures of divergent thinking, specifically the Alternate Uses Task (AUT) and the Overcoming Knowledge Constraints Task, were used to this end. Openness to aesthetic and imaginative experience was the strongest predictor of creative potential for the 3 AUT measures. Moreover, Bayesian hypothesis testing revealed that the best predictive model for AUT ideational fluency and AUT overall originality was one that included only Openness, whereas the best predictive model for AUT peak originality, or the propensity to generate highly original responses, included Openness, as well as IQ and Engagement in Creative Hobbies. No group differences in creative potential were found between the three age cohorts (aged 14-15, 16-17, and 18-20). The study not only confirms the importance of openness to aesthetic and imaginative experience as a predictor of creative potential in adolescents and young adults, but also indicates the necessity to consider the combined and differentiated impact of individual and contextual factors in different facets of creative ideation

Una nova espècie del gènere Oestophora Hesse 1907 (Gastropoda: Pulmonata: Helicodontidae) del Pleistocè superior de Mallorca (Illes Balears, Mediterrània occidental)

Abstract not availabl

V-Shape Liquid Crystal-Based Retromodulator Air to Ground Optical Communications

This paper describes the use of a 2D liquid crystal retro-modulator as a free space, wireless, optical link. The retro-modulator is made up of a retro-reflecting cornercube onto which 2 cascaded V-shape smectics liquid crystal modulators are mounted. The communication link differs with respect to more conventional optical links in not using amplitude (nor frequency) modulation, but instead state-of-polarisation (SOP) modulation known as Polarisation Shift Keying (PolSK). PolSK has the advantage over amplitude modulation, that it is less sensitive to changes in the visibility of the atmosphere, and increases inherently the bandwidth of the link. The implementation of PolSK both in liquid crystal based and in retro-modulated communication are novelties

The RASSCALS: An X-ray and Optical Study of 260 Galaxy Groups

We describe the ROSAT All-Sky Survey-Center for Astrophysics Loose Systems (RASSCALS), the largest X-ray and optical survey of low mass galaxy groups to date. We draw 260 groups from the combined Center for Astrophysics and Southern Sky Redshift Surveys, covering one quarter of the sky to a limiting Zwicky magnitude of 15.5. We detect 61 groups (23%) as extended X-ray sources. The statistical completeness of the sample allows us to make the first measurement of the X-ray selection function of groups, along with a clean determination of their fundamental scaling laws. We find robust evidence of similarity breaking in the relationship between the X-ray luminosity and velocity dispersion. Groups with sigma < 340 km/s are overluminous by several orders of magnitude compared to the familiar LX ~ sigma^4 law for higher velocity dispersion systems. An understanding of this break depends on the detailed structure of groups with small velocity dispersions sigma < 150 km/s.Comment: 16 pages, including 6 figures. To appear in The Astrophysical Journa

Sexual Function in Women with Breast Cancer : An Evidence Map of Observational Studies

Breast cancer (BC) is the leading cause of cancer in women, and has implications for sexual function (SF). In this study, we used an evidence map to identify, describe, and organise the current available evidence regarding SF in women with BC. We searched the MEDLINE, PsycINFO, and CINAHL databases for observational studies assessing SF in women with BC published in English, Spanish, Portuguese, and French between 2000 and 2021 (sample ≥ 50 women). Of the 64 included studies (13,257 women with BC), 58 were published since 2010. Women who were married, partnered, or in relationships represented 74.1% of the entire sample. Only a single study was conducted on women representing a sexual minority. We identified 22 assessment instruments and 40 sexual dysfunction (SdF) domains. The number of publications on SF in women with BC has increased in the last 10 years, but still remains low. Some groups of women are underrepresented, and some SdF domains are underdiagnosed, with the assessment instrument used affecting which domains are studied. Women with BC need to be better screened, as their quality of life (QoL) is affected by Sd

Asymptomatic Carotid Stenosis and Cognitive Improvement using Transcervical Stenting with Protective Flow Reversal Technique

ObjectivesThe relationship between carotid artery stenosis and cognitive function in individuals without a history of stroke is not clear. The possible pathomechanisms of cognitive impairment include silent embolization and hypoperfusion. In this study the aim was to assess cognitive changes after transcervical carotid artery stenting with proximal cerebral protection by flow reversal in patients with asymptomatic carotid stenosis, a novel technique that has been proved to decrease the number intraoperative emboli.Methods25 consecutive patients were assessed, of which 22 were men (88%) mean age of 74 years with severe asymptomatic carotid stenosis who underwent revascularization by carotid artery stenting (CAS) with flow reversal. Patients were evaluated 1 day before and 6 months after the procedure using a standardized neuropsychological battery. Test scores were adjusted according to age, sex, education level and were standardized (0–100). The mean of all the cognitive function scores yielded the global cognitive score (GCS).ResultsThere were no neurological complications during the procedure or during hospitalization in any patient. No deaths or cardiac complications occurred in any patient. The pre-procedure neuropsychological study showed cognitive impairment in: information processing speed in 15 patients (62.5%), visuospatial function in 14 (56.0%), memory in 18 (72.0%), executive functions in 14 (56.0%), language in three (12.0%), attention in 10 (40.0%), and global cognitive performance in eight (32.0%). Comparison of these scores with those obtained 6-month post-procedure showed significant improvement in GCS in all patients (p = .002), with a particularly marked gain in information processing speed (p = .018). Although significant improvement was not found for the remaining cognitive functions assessed, some gain was documented, and there was no deterioration.ConclusionsRevascularization by transcervical CAS with flow reversal for cerebral protection results in improved neurocognitive performance in asymptomatic elderly patients with severe carotid artery stenosis

Security devices based on liquid crystals doped with a colour dye

Liquid crystal properties make them useful for the development of security devices in applications of authentication and detection of fakes. Induced orientation of liquid crystal molecules and birefringence are the two main properties used in security devices. Employing liquid crystal and dichroic colorants, we have developed devices that show, with the aid of a polarizer, multiple images on each side of the device. Rubbed polyimide is used as alignment layer on each substrate of the LC cell. By rubbing the polyimide in different directions in each substrate it is possible to create any kind of symbols, drawings or motifs with a greyscale; the more complex the created device is, the more difficult is to fake it. To identify the motifs it is necessary to use polarized light. Depending on whether the polarizer is located in front of the LC cell or behind it, different motifs from one or the other substrate are shown. The effect arises from the dopant colour dye added to the liquid crystal, the induced orientation and the twist structure. In practice, a grazing reflection on a dielectric surface is polarized enough to see the effect. Any LC flat panel display can obviously be used as backlight as well