532 research outputs found

    Laser therapy in ROP: a literature review and our experience

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    Introduction: Retinopathy of prematurity (ROP) is a serious, vision threatening disease and among the leading causes of irreversible loss of vision. It affects prematurely born children, predominantly prior to the 32nd GW or with a body weight at birth below 1500 g. The highest risk for the development of ROP includes the time period of two weeks before to two weeks after the supposed due date. Materials and Methods: We included 10 prematurely born children with ROP requiring therapy. All of the children were screened by indirect ophthalmoscopy and the condition was documented by RetCam imaging. The treatment was conducted by the application of 810 nm diode laser. Results: Nine out of the 10 children were born before 32 GW and were with a body weight at birth below 1500 g. The disease was bilateral in 9 of the children. Laser therapy was applied to all 10 children and 18 eyes. Discussion and Conclusion: The active ophthalmological screening of all children born before 32 GW and with a body weight at birth below 1500 g, including all new-born children at risk, and the application of early laser treatment are the basis for the prevention of the development of irreversible visual loss

    Postsocialist disability matrix

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    This paper explores injustices experienced by disabled people in the postsocialist countries of Central and Eastern Europe. Drawing on Nancy Fraser’s theory of social justice, the analysis proposes a ‘matrix’ that reveals the negative impact of two factors – state socialist legacy and postsocialist neoliberalization – on disabled people’s parity of participation in three dimensions of justice – economic redistribution, cultural recognition, and political representation. The legacy of state socialism has underpinned: segregated service provision; medical-productivist understanding of disability for assessment purposes; denial of disability on everyday level; and weak disability organizing. Neoliberal restructuring has resulted in: retrenchment of disability support through decentralization, austerity, and workfare; stigmatization of ‘dependency’ through the discourse of ‘welfare dependency’; responsibilization of disabled people; and depoliticization of disability organizations by restricting their activities to service provision and incorporating them in structures of tokenistic participation. The analysis is informed by reports and academic studies of disability in the postsocialist region

    Purity-bounded uncertainty relations in multidimensional space -- generalized purity

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    Uncertainty relations for mixed quantum states (precisely, purity-bounded position-momentum relations, developed by Bastiaans and then by Man'ko and Dodonov) are studied in general multi-dimensional case. An expression for family of mixed states at the lower bound of uncertainty relation is obtained. It is shown, that in case of entropy-bounded uncertainty relations, lower-bound state is thermal, and a transition from one-dimensional problem to multi-dimensional one is trivial. Results of numerical calculation of the relation lower bound for different types of generalized purity are presented. Analytical expressions for general purity-bounded relations for highly mixed states are obtained.Comment: 12 pages, 2 figures. draft version, to appear in J. Phys. A Partially based on a poster "Multidimensional uncertainty relations for states with given generalized purity" presented on X Intl. Conf. on Quantum Optics'2004 (Minsk, Belarus, May 30 -- June 3, 2004) More actual report is to be presented on ICSSUR-2005, Besan\c{c}on, France and on EQEC'05, Munich. V. 5: amended article after referees' remark

    Kv2.1 channels prevent vasomotion and safeguard myogenic reactivity in rat small superior cerebellar arteries

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    Vascular smooth muscle voltage-gated potassium (Kv) channels have been proposed to contribute to myogenic autoregulation. Surprisingly, in initial experiments, we observed that the Kv2 channel inhibitor stromatoxin induced vasomotion without affecting myogenic tone. Thus, we tested the hypothesis that Kv2 channels contribute to myogenic autoregulation by fine-tuning the myogenic response. Expression of Kv2 channel mRNA was determined using real-time PCR and ‘multiplex’ single-cell RT-PCR. Potassium currents were measured using the patch-clamp technique. Contractile responses of intact arteries were studied using isobaric myography. Expression of Kv2.1 but not Kv2.2 channels was detected in intact rat superior cerebellar arteries and in single smooth muscle cells. Stromatoxin, a high-affinity inhibitor of Kv2 channels, reduced smooth muscle Kv currents by 61% at saturating concentrations (EC50 36 nmol/L). Further, stromatoxin (10–100 nmol/L) induced pronounced vasomotion in 48% of the vessels studied. In vessels not exhibiting vasomotion, stromatoxin did not affect myogenic reactivity. Notably, in vessels exhibiting stromatoxin-induced vasomotion, pressure increases evoked two effects: First, they facilitated the occurrence of random vasodilations and/or vasoconstrictions, disturbing the myogenic response (24% of the vessels). Second, they modified the vasomotion by decreasing its amplitude and increasing its frequency, thereby destabilizing myogenic tone (76% of the vessels). Our study demonstrates that (i) Kv2.1 channels are the predominantly expressed Kv channels in smooth muscle cells of rat superior cerebellar arteries, and (ii) Kv2.1 channels provide a novel type of negative feedback mechanism in myogenic autoregulation by preventing vasomotion and thereby safeguarding the myogenic response

    Photonic realization of the relativistic Kronig-Penney model and relativistic Tamm surface states

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    Photonic analogues of the relativistic Kronig-Penney model and of relativistic surface Tamm states are proposed for light propagation in fibre Bragg gratings (FBGs) with phase defects. A periodic sequence of phase slips in the FBG realizes the relativistic Kronig-Penney model, the band structure of which being mapped into the spectral response of the FBG. For the semi-infinite FBG Tamm surface states can appear and can be visualized as narrow resonance peaks in the transmission spectrum of the grating
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