Cognition, ocular accommodation, and cardiovascular function in emmetropes and late-onset myopes

PURPOSE. To investigate objectively and noninvasively the role of cognitive demand on autonomic control of systemic cardiovascular and ocular accommodative responses in emmetropes and myopes of late-onset. METHODS. Sixteen subjects (10 men, 6 women) aged between 18 and 34 years (mean ± SD: 22.6 ± 4.4 years), eight emmetropes (EMMs; mean spherical equivalent [MSE] refractive error ± SD: 0.05 ± 0.24 D) and eight with late-onset myopia (LOMs; MSE ± SD: -3.66 ± 2.31 D) participated in the study. Subjects viewed stationary numerical digits monocularly within a Badal optical system (at both 0.0 and -3.0 D) while performing a two-alternative, forced-choice paradigm that matched cognitive loading across subjects. Five individually matched cognitive levels of increasing difficulty were used in random order for each subject. Five 20-second, continuous-objective recordings of the accommodative response measured with an open-view infrared autorefractor were obtained for each cognitive level, whereas simultaneous measurement of heart rate was continuously recorded with a finger-mounted piezoelectric pulse transducer for 5 minutes. Fast Fourier transformation of cardiovascular function allowed the relative power of the autonomic components to be assessed in the frequency domain, whereas heart period gave an indication of the time-domain response. RESULTS. Increasing the cognitive demand led to a significant reduction in the accommodative response in all subjects (0.0 D: by -0.35 ± 0.33 D; -3.0 D: by -0.31 ± 0.40 D, P < 0.001). The greater lag of LOMs compared with EMMs was not significant (P = 0.07) at both distance (0.38 ± 0.35 D) and near (0.14 ± 0.42 D). Mean heart period reduced with increasing levels of workload (P < 0.0005). LOMs exhibited a relative elevation in sympathetic system activity compared to EMMs. Within refractive groups, however, accommodative shifts with increasing cognition correlated with parasympathetic activity (r = 0.99, P < 0.001), more than with sympathetic activity (r = 0.62, P > 0.05). CONCLUSIONS. In an equivalent workload paradigm, increasing cognitive demand caused a reduction in accommodative response that was attributable principally to a concurrent reduction in the relative power of the parasympathetic component of the autonomic nervous system (ANS). The disparity in accommodative response between EMMs and LOMs, however, appears to be augmented by changes in the sympathetic nervous component of the systemic ANS. Copyright © Association for Research in Vision and Ophthalmology.

Problems with formative and higher-order reflective variables

Cadogan and Lee (this issue) discuss the problems inherent in modeling formative latent variables as endogenous. In response to the commentaries by Rigdon (this issue) and Finn and Wang (this issue), the present article extends the discussion on formative measures. First, the article shows that regardless of whether statistical identification is achieved, researchers are unable to illuminate the nature of a formative latent variable. Second, the study clarifies issues regarding formative indicator weighting, highlighting that the weightings of formative components should be specified as part of the construct definition. Finally, the study shows that higher-order reflective constructs are invalid, highlights the damage their use can inflict on theory development and knowledge accumulation, and provides recommendations on a number of alternative models which should be used in their place (including the formative model). © 2012 Elsevier Inc.

Improper use of formative endogenous variables

Researchers often develop and test conceptual models containing formative variables. In many cases, these formative variables are specified as being endogenous. This article provides a clarification of formative variable theory, distinguishing between the formative latent variable and the formative composite variable. When an endogenous latent variable relies on formative indicators for measurement, empirical studies can say nothing about the relationship between exogenous variables and the endogenous formative latent variable: conclusions can only be drawn regarding the exogenous variables' relationships with a composite variable. The authors also show the dangers associated with developing theory about antecedents to endogenous formative variables at the (aggregate) formative latent variable level. Modeling relationships with endogenous formative variables at the (disaggregate) indicator level informs richer theory development, and encourages more precise empirical testing. When antecedents' relationships with endogenous formative variables are modeled at the formative latent variable level rather than the formative indicator level, theory construction can verge on the superficial, and empirical findings can be ambiguous in substantive meaning.

Building bank brands:how leadership behavior influences employee commitment

Front line employees are critical to service brand success, as their performance brings brand promises to life. Banking employees, like others, must remain committed to their employers, to live the brand, particularly during periods of economic uncertainty and customer frustration. Employees' commitment influences their brand adoption and brand-supporting behavior during service encounters. Effective leadership fosters employee commitment and brand supporting behaviors. This study examines the nature of employee commitment in banking, distinguishing between affective, continuance and normative commitment. The study explores bank leaders, examining whether initiating structure leader behavior or considerate leader behavior is most effective in encouraging employee commitment. Data from a sample of 438 employees in a leading Irish bank reveals the optimal leadership style for employee commitment. © 2012 Elsevier Inc.

Introduction : thought leadership in brand management

This JBR Special Issue contains ten articles developed from presentations at the Seventh Annual Thought Leaders' International Conference on Brand Management, held at Universitá della Svizzera italiana in Lugano, Switzerland in March 2011. The conference organizing committee received submissions and following a double blind reviewing process papers were accepted for presentation at the conference. After the conference all authors wishing to submit papers for this Special Edition had the opportunity to revise their papers and submit them. A further round of rigorous double-blind reviewing resulted in the selection of ten articles. This introduction presents an overview of this thought-leading research into brand management. © 2012 Elsevier Inc.

Critical noise levels for low-density parity check decoding

We determine the critical noise level for decoding low-density parity check error-correcting codes based on the magnetization enumerator (M), rather than on the weight enumerator (W) employed in the information theory literature. The interpretation of our method is appealingly simple, and the relation between the different decoding schemes such as typical pairs decoding, MAP, and finite temperature decoding (MPM) becomes clear. In addition, our analysis provides an explanation for the difference in performance between MN and Gallager codes. Our results are more optimistic than those derived using the methods of information theory and are in excellent agreement with recent results from another statistical physics approach.

Um estudo sobre o perfil sexual e reprodutivo das adolescentes de um serviço de referência no município de Natal/RN

Adolescence is seen as a phase of life marked by a series of physical and behavioral changes, which leads to certain risk situations, such as early sexual activity, pregnancy and the occurrence of sexually transmitted diseases. Based on this statement, this research aimed generally: meet the sexual and reproductive adolescents of a reference service in Natal profile. Specifically describe the socioeconomic, sexual and reproductive individual and family characteristics of the population in question, but also verify possible association between pregnancy and age of onset of sexual activity with the socioeconomic aspects. The sectional study conducted in the database from the records of 463 adolescents seeking care in a referral center in Sexual and Reproductive Health in the period March 2011 to June 2012. The data collected were subjected to analysis by Excel 2007 and Statistical Package for Social Sciences (SPSS) 17.0. For data analysis, descriptive statistics, with absolute numbers and percentages was used, and its presentation by means of distribution and frequency tables. Results showed that the parents of these adolescents (65.7% - father; 57.8% - mother), had primary education; family income less than two minimum wages (66.2%); any type of chemical dependency in the family (33.5%) and presence of domestic violence (20.6%). A higher probability of pregnancy was verified when the mother had only primary education (26.3%), persons other than the father or mother contributed to family income (33.3%) and (26%) when there was substance abuse in the family early onset of sexual activity was observed when the mother had primary education (57.3%), persons other than the father or mother contributed to family income (63.1%) and the use of drugs / alcohol as a problem family (67.6%). It was concluded that such vulnerabilities appear as a reflection of the low social status of these young people, aggravated by emotional inheritance that is offered to every individual from birth. These findings may perhaps, support public health surveillance policies for adolescents in several areas

A randomized trial comparing the diagnostic accuracy of visual inspection with acetic acid to Visual Inspection with Lugol's Iodine for cervical cancer screening in HIV-infected women.

Visual inspection with Acetic Acid (VIA) and Visual Inspection with Lugol’s Iodine (VILI) are increasingly recommended in various cervical cancer screening protocols in low-resource settings. Although VIA is more widely used, VILI has been advocated as an easier and more specific screening test. VILI has not been well-validated as a stand-alone screening test, compared to VIA or validated for use in HIV-infected women. We carried out a randomized clinical trial to compare the diagnostic accuracy of VIA and VILI among HIV-infected women. Women attending the Family AIDS Care and Education Services (FACES) clinic in western Kenya were enrolled and randomized to undergo either VIA or VILI with colposcopy. Lesions suspicious for cervical intraepithelial neoplasia 2 or greater (CIN2+) were biopsied. Between October 2011 and June 2012, 654 were randomized to undergo VIA or VILI. The test positivity rates were 26.2% for VIA and 30.6% for VILI (p = 0.22). The rate of detection of CIN2+ was 7.7% in the VIA arm and 11.5% in the VILI arm (p = 0.10). There was no significant difference in the diagnostic performance of VIA and VILI for the detection of CIN2+. Sensitivity and specificity were 84.0% and 78.6%, respectively, for VIA and 84.2% and 76.4% for VILI. The positive and negative predictive values were 24.7% and 98.3% for VIA, and 31.7% and 97.4% for VILI. Among women with CD4+ count < 350, VILI had a significantly decreased specificity (66.2%) compared to VIA in the same group (83.9%, p = 0.02) and compared to VILI performed among women with CD4+ count ≥ 350 (79.7%, p = 0.02). VIA and VILI had similar diagnostic accuracy and rates of CIN2+ detection among HIV-infected women.

Mg/Ca ratio, Sr/Ca ratio and stable isotopes of the foraminifera Oridorsalis umbonatus in surface sediment samples

We investigate the influence of carbonate system parameters (carbonate ion concentration, [CO3**2-]; carbonate ion saturation, Delta [CO3**2-]) on the trace element and stable isotope ratios in the endobenthic foraminifera Oridorsalis umbonatus. Data from modern core top samples from the Namibian continental slope suggest that the shell composition of this species is influenced by the chemistry of the pore-water. For these organic-rich sediments, the impact of ocean bottom water properties on both pore-water and shell chemistry is surprisingly small. Sr/Ca correlates positively with [CO3**2-] and to a lesser extent with Delta [CO3**2-], which is opposed to previous results. A [CO3**2-] decrease of 10 µmol/kg leads to an increase of 0.05 mmol/mol in Sr/Ca. We observe a correlation between shell d18O (corrected for temperature and d18O seawater) and [CO3**2-], however, the variability of the corrected d18O is close to the analytical limit. No clear dependences were observed for d13C and Mg/Ca.

Class-D audio amplifiers with negative feedback

There are many different designs for audio amplifiers. Class-D, or switching, amplifiers generate their output signal in the form of a high-frequency square wave of variable duty cycle (ratio of on time to off time). The square-wave nature of the output allows a particularly efficient output stage, with minimal losses. The output is ultimately filtered to remove components of the spectrum above the audio range. Mathematical models are derived here for a variety of related class-D amplifier designs that use negative feedback. These models use an asymptotic expansion in powers of a small parameter related to the ratio of typical audio frequencies to the switching frequency to develop a power series for the output component in the audio spectrum. These models confirm that there is a form of distortion intrinsic to such amplifier designs. The models also explain why two approaches used commercially succeed in largely eliminating this distortion; a new means of overcoming the intrinsic distortion is revealed by the analysis. Copyright (2006) Society for Industrial and Applied Mathematics

Impacto de la emigración sobre la morbilidad psíquica en los escolares, hijos de padres emigrantes de las escuelas de la parroquia Chiquintad del Cantón Cuenca, de la provincia del Azuay, año lectivo 2008-2009

Se realiza un estudio para determinar la prevalencia de migración y su efecto sobre la morbilidad psíquica en los escolares hijos de padres emigrantes. Participaron 651 niños de las escuelas de la parroquia Chiquintad del cantón Cuenca en el período 2008-2009 a quienes se aplicó una encuesta relacionada a la migración, que incluyó el test de valoración de funcionalidad familiar y el test de Stott modificado para niños, para los síntomas principales de: retraso del aprendizaje, depresión, ansiedad y agresividad. La prevalencia de migración fue el 31.3%, encontrándose que el padre es quien más migra (59.3%), principal lugar de destino Estados Unidos (88.2%), los hijos de emigrante quedan bajo la tutela de sus abuelos (89.9%), se encontró una prevalencia de retraso del aprendizaje de 6%, correspondiente 56.4% a hijos de emigrantes RP de 2.83 (IC:1.53-5.22), depresión 2.6%, en hijos de emigrantes 52.9% con un RP 2.46 (IC:0.96-6.29); ansiedad 2.2%, de los cuales 50% son hijos de emigrantes (RP:2.19, IC:0.77-6.16) y agresividad 2.69%, 55.2% en hijos de emigrantes (RP:2.69, IC:1.32-5.50), disfuncionalidad familiar 35.7% de familias de emigrantes (RP1.21, IC:0.66 2.23).

Assessment of iodine intake and related cognitive function impairments in elementary schoolchildren from Terceira Island, Azores (Portugal)

Dissertação de Mestrado, Ciências Biomédicas, 28 de Junho de 2016, Universidade dos Açores.

Evolution of psychosocial factors at work in a French region

International audience