From Simple Liquids to Surgical Instruments: On the History of Ophthalmo-Viscosurgical Devices (OVD)

Nowadays, OVDs are regarded as standard tools in ophthalmic surgery. Their discovery and development started about 70 years ago, in 1934, with isolating hyaluronic acid as the substance o f the vitreous body o f the human eye. Sodium Hyaluronate was the first substance used as an OVD and is now the most widely used material for OVDs used in ophthalmic surgery. It has become “the gold standard” to which all other viscoelastics are compared. Since the introduction of viscoelastic substances in the 1970s the properties of these agents have improved the quality o f anterior segment surgery. Therefore OVDs had — and still have — a great impact on the success of ophthalmic surgery — especially o f cataract surgery and intraocular lens implantation. In vivo studies have proven that the molecular and chemical structure of hyaluronic acid is ideal. Interactions between molecules and receptor tissues and inflammatory and immunogenic reactions have also been studied extensively. This article shows the historical development o f the different substances used nowadays and their properties.Preparaty wiskoelastyczne są obecnie uważane za standardowe narzędzia w operacjach okulistycznych. Ich odkrycie i rozwój zostały poprzedzone wyizolowaniem w 1934 roku kwasu hialuronowego z ciała szklistego ludzkiego oka. Hialuronian sodu był pierwszą substancją używaną w charakterze preparatu wiskoelastycznego i obecnie jest najpowszechniej używanym materiałem wiskoelastycznym w operacjach okulistycznych, stając się wzorcem, do którego porównywane są inne substancje wiskoelastyczne. Od momentu zastosowania w latach siedemdziesiątych materiały te, dzięki swoim właściwościom, przyczyniły się do poprawy wyników operacyjnych w przednim odcinku oka. Preparaty wiskoelastyczne miały i nadal mają wielki wpływ na powodzenie zabiegów okulistycznych, a zwłaszcza operacji usunięcia zaćmy i wszczepienia sztucznej soczewki wewnątrzgałkowej. Badania in vivo wykazały, że struktura molekularna i chemiczna kwasu hialuronowego jest idealna. Badane były również wzajemne oddziaływania między kwasem hialuronowym a tkankami oka oraz reakcje zapalne i immunologiczne. Ten artykuł przedstawia historię rozwoju obecnie stosowanych materiałów wiskoelastycznych oraz ich właściwości.Andrzej Grzybowsk

Loosely bound hyperons in the SU(3) Skyrme model

Hyperon pairs bound in deuteron like states are obtained within the SU(3) Skyrme model in agreement with general expectations from boson exchange models. The central binding from the flavor symmetry breaking terms increases with the strangeness contents of the interacting baryons whereas the kinetic non-linear $\sigma$-model term fixes the spin and isospin of the bound pair. We give a complete account of the interactions of octet baryons within the product approximation to baryon number $B=2$ configurations.Comment: 35 pages REVTEX including 2 figs, with 3 further figs available on request from [email protected] or from [email protected] SI-94-TP3S2; STPHY-Th/94-

Formation of helical states in wormlike polymer chains

We propose a potential for wormlike polymer chains which can be used to model the low-temperature conformational structures. We successfully reproduced helix ground states up to 6.5 helical loops, using the multicanonical Monte Carlo simulation method. We demonstrate that the coil-helix transition involves four distinct phases: coil(gaslike), collapsed globular(liquidlike), and two helical phases I and II (both solidlike). The helix I phase is characterized by a helical structure with dangling loose ends, and the helix II phase corresponds to a near perfect helix ordering in the entire crystallized chain.Comment: 5 pages, 2 figures, Submitted to PR

Crypto-unitary forms of quantum evolution operators

For the description of quantum evolution, the use of a manifestly time-dependent quantum Hamiltonian $\mathfrak{h}(t) =\mathfrak{h}^\dagger(t)$ is shown equivalent to the work with its simplified, time-independent alternative $G\neq G^\dagger$. A tradeoff analysis is performed recommending the latter option. The physical unitarity requirement is shown fulfilled in a suitable ad hoc representation of Hilbert space.Comment: 15 p

JJ-self-adjoint operators with C\mathcal{C}-symmetries: extension theory approach

A well known tool in conventional (von Neumann) quantum mechanics is the self-adjoint extension technique for symmetric operators. It is used, e.g., for the construction of Dirac-Hermitian Hamiltonians with point-interaction potentials. Here we reshape this technique to allow for the construction of pseudo-Hermitian ($J$-self-adjoint) Hamiltonians with complex point-interactions. We demonstrate that the resulting Hamiltonians are bijectively related with so called hypermaximal neutral subspaces of the defect Krein space of the symmetric operator. This symmetric operator is allowed to have arbitrary but equal deficiency indices . General properties of the $\cC$ operators for these Hamiltonians are derived. A detailed study of $\cC$-operator parametrizations and Krein type resolvent formulas is provided for $J$-self-adjoint extensions of symmetric operators with deficiency indices . The technique is exemplified on 1D pseudo-Hermitian Schr\"odinger and Dirac Hamiltonians with complex point-interaction potentials

Small whole heart volume predicts cardiovascular events in patients with stable chest pain: insights from the PROMISE trial

Objectives The size of the heart may predict major cardiovascular events (MACE) in patients with stable chest pain. We aimed to evaluate the prognostic value of 3D whole heart volume (WHV) derived from non-contrast cardiac computed tomography (CT). Methods Among participants randomized to the CT arm of the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE), we used deep learning to extract WHV, defined as the volume of the pericardial sac. We compared the WHV across categories of cardiovascular risk factors and coronary artery disease (CAD) characteristics and determined the association of WHV with MACE (all-cause death, myocardial infarction, unstable angina; median follow-up: 26 months). Results In the 3798 included patients (60.5 +/- 8.2 years; 51.5% women), the WHV was 351.9 +/- 57.6 cm(3)/m(2). We found smaller WHV in no- or non-obstructive CAD, women, people with diabetes, sedentary lifestyle, and metabolic syndrome. Larger WHV was found in obstructive CAD, men, and increased atherosclerosis cardiovascular disease (ASCVD) risk score (p < 0.05). In a time-to-event analysis, small WHV was associated with over 4.4-fold risk of MACE (HR (per one standard deviation) = 0.221; 95% CI: 0.068-0.721; p = 0.012) independent of ASCVD risk score and CT-derived CAD characteristics. In patients with non-obstructive CAD, but not in those with no- or obstructive CAD, WHV increased the discriminatory capacity of ASCVD and CT-derived CAD characteristics significantly. Conclusions Small WHV may represent a novel imaging marker of MACE in stable chest pain. In particular, WHV may improve risk stratification in patients with non-obstructive CAD, a cohort with an unmet need for better risk stratification

On the similarity of Sturm-Liouville operators with non-Hermitian boundary conditions to self-adjoint and normal operators

We consider one-dimensional Schroedinger-type operators in a bounded interval with non-self-adjoint Robin-type boundary conditions. It is well known that such operators are generically conjugate to normal operators via a similarity transformation. Motivated by recent interests in quasi-Hermitian Hamiltonians in quantum mechanics, we study properties of the transformations in detail. We show that they can be expressed as the sum of the identity and an integral Hilbert-Schmidt operator. In the case of parity and time reversal boundary conditions, we establish closed integral-type formulae for the similarity transformations, derive the similar self-adjoint operator and also find the associated "charge conjugation" operator, which plays the role of fundamental symmetry in a Krein-space reformulation of the problem.Comment: 27 page

Effects of motifs in music therapy on the attention of children with externalizing behavior problems

Recent studies highlight the role of attention (i.e., executive attention and joint attention) in the negative association between children’s externalizing behavior problems (EBPs) and self-regulation. In music therapy improvisation, “Motifs” represent a repeated and meaningful use of freely improvised or structured music. They have been reported to be effective in drawing attention toward joint musical engagement. This study aimed to examine the effects of clinically derived motifs on the attention of a child with EBPs. Video microanalysis of four therapy sessions was employed. Interaction segments with/without motifs were then selected for analysis: (a) Executive attention measurement: a two-way analysis of variance (ANOVA) was conducted to examine the effects of Motifs (Factor I) across sessions (Factor II) on the duration of interaction segments. (b) Joint attention measurement: another two-way ANOVA investigated the effects of these two factors on the duration of joint attentive responses in each segment. Results showed that (a) the segments with Motifs tended to decrease in duration throughout the sessions, while (b) these segments showed a significant increase in proportions of joint attentional responses. These findings suggest a positive effect of Motifs on enhancing efficiency of joint attention execution over time, indicating the child’s recognition of the Motifs through learning

Spontaneous PT-Symmetry Breaking for Systems of Noncommutative Euclidean Lie Algebraic Type

We propose a noncommutative version of the Euclidean Lie algebra E 2. Several types of non-Hermitian Hamiltonian systems expressed in terms of generic combinations of the generators of this algebra are investigated. Using the breakdown of the explicitly constructed Dyson maps as a criterium, we identify the domains in the parameter space in which the Hamiltonians have real energy spectra and determine the exceptional points signifying the crossover into the different types of spontaneously broken PT-symmetric regions with pairs of complex conjugate eigenvalues. We find exceptional points which remain invariant under the deformation as well as exceptional points becoming dependent on the deformation parameter of the algebra

Unique establishment of procephalic head segments is supported by the identification of cis-regulatory elements driving segment-specific segment polarity gene expression in Drosophila

Anterior head segmentation is governed by different regulatory mechanisms than those that control trunk segmentation in Drosophila. For segment polarity genes, both initial mode of activation as well as cross-regulatory interactions among them differ from the typical genetic circuitry in the trunk and are unique for each of the procephalic segments. In order to better understand the segment-specific gene network responsible for the procephalic expression of the earliest active segment polarity genes wingless and hedgehog, we started to identify and analyze cis-regulatory DNA elements of these genes. For hedgehog, we could identify a cis-regulatory element, ic-CRE, that mediates expression specifically in the posterior part of the intercalary segment and requires promoter-specific interaction for its function. The intercalary stripe is the last part of the metameric hedgehog expression pattern that appears during embryonic development, which probably reflects the late and distinct establishment of this segment. The identification of a cis-regulatory element that is specific for one head segment supports the mutant-based observation that the expression of segment polarity genes is governed by a unique gene network in each of the procephalic segments. This provides further indication that the anterior-most head segments represent primary segments, which are set up independently, in contrast to the secondary segments of the trunk, which resemble true repetitive units