13,637 research outputs found

    Pain Sensitivity Associated With the Length of the Maximum Interblink Period.

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    Pain sensitivity has been identified as a factor that affects how individuals answer dry eye questionnaires, but it is unknown how it affects ocular discomfort. This study used the time that individuals could refrain from blinking as an indicator of ocular discomfort and set out to determine whether it was related to pain sensitivity, while adjusting for ocular surface conditions.Subjects first completed the Pain Sensitivity Questionnaire to quantify pain sensitivity levels. Exposed interpalpebral area, tear meniscus height, tear-film lipid layer thickness, ocular surface cooling, and noninvasive tear breakup were assessed. Subjects were then asked to refrain from blinking until the initial onset of discomfort, which was termed "the maximum interblink period" (MIBP), while ocular surface cooling rate was simultaneously measured. Subjects were seen for four visits over a course of 2 days.Forty-two subjects (36 females, 6 males) completed the study, with a mean (SD) age of 23.2 (3.8) years. A longer MIBP was associated with decreased pain sensitivity (P = 0.04), lower ocular surface cooling rate (P < 0.001), and Asian ethnicity (P = 0.005). Based on the results from the mixed-effect model, it is estimated that individuals would be able to refrain from blinking for an additional 4 seconds if they had the lowest (0.6) compared to the highest (6.1) pain sensitivity in the study cohort.The Pain Sensitivity Questionnaire was associated with the MIBP length even after adjusting for ocular surface conditions, which suggests that pain sensitivity plays a role in influencing how ocular discomfort is perceived

    Contact lenses wettability in vitro: effect of surface-active ingredients.

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    PurposeTo investigate the release of surface-active agents (surfactants) from unworn soft contact lenses (SCLs) and their influence on the lens surface wettability in vitro.MethodsSurface tension (ST) of blister pack solutions was measured by pendant-drop technique. STs at the air-aqueous interface and contact angles (CAs) of four conventional and seven silicone hydrogel SCLs were evaluated in a dynamic-cycling regime using a modified captive-bubble tensiometer-goniometer. Measurements were performed immediately after removal from blister packs, and after soaking in a glass vial filled with a surfactant-free solution, which was replaced daily for 1 week. Lens surface wettability was expressed as adhesion energy according to Young equation.ResultsSTs of all blister pack solutions were lower than the reference ST of pure water (72.5 mN/m), indicating the presence of surfactants. When lenses were depleted of surfactants by soaking, the STs for all studied lenses and advancing CAs of selected lenses increased (p < 0.001). Receding CAs of all studied lenses were 12 degrees +/- 5 degrees and were not affected by the presence of surfactants. For most of the conventional lenses, the surface wettability was largely dependent on surfactants, and reduced significantly after surfactant depletion. In contrast, most silicone hydrogel lenses exhibited stable and self-sustained surface wettability in vitro.ConclusionsThe manufacturer-added surfactants affected wetting properties of all studied SCLs, although to different degrees

    Dynamical study of the possible molecular state X(3872) with the s-channel one gluon exchange interaction

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    The recently observed X(3872) resonance, which is difficult to be assigned a conventional ccˉc\bar{c} charmonium state in the quark model, may be interpreted as a molecular state. Such a molecular state is a hidden flavor four quark state because of its charmonium-like quantum numbers. The s-channel one gluon exchange is an interaction which only acts in the hidden flavor multi-quark system. In this paper, we will study the X(3872) and other similiar hidden flavor molecular states in a quark model by taking into account of the s-channel one gluon exchange interaction

    Study the Heavy Molecular States in Quark Model with Meson Exchange Interaction

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    Some charmonium-like resonances such as X(3872) can be interpreted as possible D()D()D^{(*)}D^{(*)} molecular states. Within the quark model, we study the structure of such molecular states and the similar B()B()B^{(*)}B^{(*)} molecular states by taking into account of the light meson exchange (π\pi, η\eta, ρ\rho, ω\omega and σ\sigma) between two light quarks from different mesons
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