536 research outputs found

    The effect of aberrations on objectively assessed image quality and depth of focus.

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    The effects of aberrations on image quality and the objectively assessed depth of focus (DoF) were studied. Aberrometry data from 80 young subjects with a range of refractive errors was used for computing the visual Strehl ratio based on the optical transfer function (VSOTF), and then, through-focus simulations were performed in order to calculate the objective DoF (using two different relative thresholds of 50% and 80%; and two different pupil diameters) and the image quality (the peak VSOTF). Both lower order astigmatism and higher order aberration (HOA) terms up to the fifth radial order were considered. The results revealed that, of the HOAs, the comatic terms (third and fifth order) explained most of the variations of the DoF and the image quality in this population of subjects. Furthermore, computer simulations demonstrated that the removal of these terms also had a significant impact on both DoF and the peak VSOTF. Knowledge about the relationship between aberrations, DoF, image quality, and their interactions is essential in optical designs aiming to produce large values of DoF while maintaining an acceptable level of image quality. Comatic aberration terms appear to contribute strongly towards the configuration of both of these visually important parameters

    Appointing Women to Boards: Is There a Cultural Bias?

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    Companies that are serious about corporate governance and business ethics are turning their attention to gender diversity at the most senior levels of business (Institute of Business Ethics, Business Ethics Briefing 21:1, 2011). Board gender diversity has been the subject of several studies carried out by international organizations such as Catalyst (Increasing gender diversity on boards: Current index of formal approaches, 2012), the World Economic Forum (Hausmann et al., The global gender gap report, 2010), and the European Board Diversity Analysis (Is it getting easier to find women on European boards? 2010). They all lead to reports confirming the overall relatively low proportion of women on boards and the slow pace at which more women are being appointed. Furthermore, the proportion of women on corporate boards varies much across countries. Based on institutional theory, this study hypothesizes and tests whether this variation can be attributed to differences in cultural settings across countries. Our analysis of the representation of women on boards for 32 countries during 2010 reveals that two cultural characteristics are indeed associated with the observed differences. We use the cultural dimensions proposed by Hofstede (Culture’s consequences: International differences in work-related values, 1980) to measure this construct. Results show that countries which have the greatest tolerance for inequalities in the distribution of power and those that tend to value the role of men generally exhibit lower representations of women on boards

    Variation in the modal response of retrofitted unreinforced masonry walls at different levels of damage

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    This article presents the results of an experimental campaign conducted on a set of four unreinforced masonry walls at full scale. The purpose of this study is to assess, using non-destructive methods, the impact of retrofitting and damage on the modal response of masonry wall systems. Each wall underwent a sequence of increasing cyclic displacements applied by an actuator at the upper end of the specimen. Modal tests based on vibrations were performed both before and after rehabilitation, as well as during the sequence of increasing displacements. It was demonstrated that frequencies can identify progressive damage when the maximum crack is about to occur, as well as the effect of wall retrofitting when mass contribution is considerable. However, the modal assurance criterion indicator (MAC) fails to properly identify a trend of decreasing correlations as progressive damage increases; instead, it is sensitive to detecting maximum crack and instability conditions. Furthermore, it was determined that the coordinated modal assurance criterion indicator (COMAC) does not identify the damage distribution as expected. However, the cumulative COMAC provides a useful tool for quick visualization and interpretation of COMAC behavior. Finally, a novel damage indicator was tested, MACVF, which improves the trend and successfully identifies the most damage-sensitive mode, especially when the maximum level of damage is reached, giving MAC values below 80%. In addition, frequency variations ranged from 70% to 110% when TRM and WWM retrofitting techniques were applied

    A novel PKC activating molecule promotes neuroblast differentiation and delivery of newborn neurons in brain injuries

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    Neural stem cells are activated within neurogenic niches in response to brain injuries. This results in the production of neuroblasts, which unsuccessfully attempt to migrate toward the damaged tissue. Injuries constitute a gliogenic/non-neurogenic niche generated by the presence of anti-neurogenic signals, which impair neuronal differentiation and migration. Kinases of the protein kinase C (PKC) family mediate the release of growth factors that participate in different steps of the neurogenic process, particularly, novel PKC isozymes facilitate the release of the neurogenic growth factor neuregulin. We have demonstrated herein that a plant derived diterpene, (EOF2; CAS number 2230806-06-9), with the capacity to activate PKC facilitates the release of neuregulin 1, and promotes neuroblasts differentiation and survival in cultures of subventricular zone (SVZ) isolated cells in a novel PKC dependent manner. Local infusion of this compound in mechanical cortical injuries induces neuroblast enrichment within the perilesional area, and noninvasive intranasal administration of EOF2 promotes migration of neuroblasts from the SVZ towards the injury, allowing their survival and differentiation into mature neurons, being some of them cholinergic and GABAergic. Our results elucidate the mechanism of EOF2 promoting neurogenesis in injuries and highlight the role of novel PKC isozymes as targets in brain injury regeneration

    Periodic orbits associated to Hamiltonian functions of degree four

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    We consider the Hamiltonian polynomial function H of degree fourth given by either H(x,y,{p_x},{p_y}) = \frac{1}{2}(p_x^2 + p_y^2) + \frac{1}{2}({x^2} + {y^2}) + {V_3}(x,y) + {V_4}(x,y),\,\,{\text{or}}\,H(x,y,{p_x},{p_y}) = \frac{1}{2}( - p_x^2 + p_y^2) + \frac{1}{2}( - {x^2} + {y^2}) + {V_3}(x,y) + {V_4}(x,y), where V3(x,y) and V4(x,y) are homogeneous polynomials of degree three and four, respectively. Our main objective is to prove the existence and stability of periodic solutions associated to H using the classical averaging method

    RESCUE OF HIPPO CO-ACTIVATOR YAP1 TRIGGERS DNA DAMAGE-INDUCED APOPTOSIS IN HEMATOLOGICAL CANCERS

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    Oncogene–induced DNA damage elicits genomic instability in epithelial cancer cells, but apoptosis is blocked through inactivation of the tumor suppressor p53. In hematological cancers, the relevance of ongoing DNA damage and mechanisms by which apoptosis is suppressed are largely unknown. We found pervasive DNA damage in hematologic malignancies including multiple myeloma, lymphoma and leukemia, which leads to activation of a p53–independent, pro-apoptotic network centered on nuclear relocalization of ABL1 kinase. Although nuclear ABL1 triggers cell death through its interaction with the Hippo pathway co–activator YAP1 in normal cells, we show that low YAP1 levels prevent nuclear ABL1–induced apoptosis in these hematologic malignancies. YAP1 is under the control of a serine–threonine kinase, STK4. Importantly, genetic inactivation of STK4 restores YAP1 levels, triggering cell death in vitro and in vivo. Our data therefore identify a novel synthetic–lethal strategy to selectively target cancer cells presenting with endogenous DNA damage and low YAP1 levels

    Obesity and survival in operable breast cancer patients treated with adjuvant anthracyclines and taxanes according to pathological subtypes: a pooled analysis

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    IntroductionObesity is an unfavorable prognostic factor in breast cancer (BC) patients regardless of menopausal status and treatment received. However, the association between obesity and survival outcome by pathological subtype requires further clarification.MethodsWe performed a retrospective analysis including 5,683 operable BC patients enrolled in four randomized clinical trials (GEICAM/9906, GEICAM/9805, GEICAM/2003–02, and BCIRG 001) evaluating anthracyclines and taxanes as adjuvant treatments. Our primary aim was to assess the prognostic effect of body mass index (BMI) on disease recurrence, breast cancer mortality (BCM), and overall mortality (OM). A secondary aim was to detect differences of such prognostic effects by subtype.ResultsMultivariate survival analyses adjusting for age, tumor size, nodal status, menopausal status, surgery type, histological grade, hormone receptor status, human epidermal growth factor receptor 2 (HER2) status, chemotherapy regimen, and under-treatment showed that obese patients (BMI 30.0 to 34.9) had similar prognoses to that of patients with a BMI < 25 (reference group) in terms of recurrence (Hazard Ratio [HR] = 1.08, 95% Confidence Interval [CI] = 0.90 to 1.30), BCM (HR = 1.02, 0.81 to 1.29), and OM (HR = 0.97, 0.78 to 1.19). Patients with severe obesity (BMI ≥ 35) had a significantly increased risk of recurrence (HR = 1.26, 1.00 to 1.59, P = 0.048), BCM (HR = 1.32, 1.00 to 1.74, P = 0.050), and OM (HR = 1.35, 1.06 to 1.71, P = 0.016) compared to our reference group. The prognostic effect of severe obesity did not vary by subtype.ConclusionsSeverely obese patients treated with anthracyclines and taxanes present a worse prognosis regarding recurrence, BCM, and OM than patients with BMI < 25. The magnitude of the harmful effect of BMI on survival-related outcomes was similar across subtypes

    Relación médico-paciente con Enfermedad Inflamatoria Intestinal en España

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    RESUMENIntroducción: Los pacientes con Enfermedad Inflamatoria Intestinal (EII) al llevar tratamiento crónico precisan seguimiento de su médico especialista de por vida.La relación médico-paciente es esencial para que los resultados de los tratamientos sean adecuados y que exista buena adherencia a los mismos. Objetivos: 1) Evaluar el grado de empatía de los médicos especialistas percibida por los pacientes con EII. 2) Evaluar si la percepción de dicha empatía se ve modificada en función del sexo y la edad del médico y del paciente. Métodos: Se trata de un estudio observacional transversal basado en encuestas anónimas realizadas a pacientes con EII del Hospital Clínico durante febrero del 2020. La encuesta constaba de la escala CARE (Consultation and Relational Empathy) que evalúa la empatía en la relación médico-paciente y 5 preguntas adicionales. Resultados: Se incluyeron 145 pacientes, 56,6% eran hombres y 43,4% mujeres, con una edad media de 44,65 años y 43,89 años respectivamente. El 60,7% de los pacientes fue atendido por un médico mujer. Al 56,6% de los pacientes le atendió un médico de 40 a 59 años, al 35,2% uno ≥ 60 años y al 8,3% uno 40 años atendidos por médicos >40 años daban puntuaciones significativamente más altas que el resto (47 puntos vs. 38, 39 y 45 con las otras combinaciones, p=0,032). Al 99,3% (144/145) de los pacientes les pareció importante lo valorado por la escala CARE. Conclusiones: La relación entre médico-paciente con EII en el Hospital Clínico es muy buena, correlacionándose con la empatía que el paciente percibe. Al estudiarla en función del sexo y edad del paciente y del médico no se encuentran diferencias estadísticamente significativas, salvo en la combinación edad médico/paciente. <br /
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