Vortex beam as a positioning tool Popiołek-Masajada, Agnieszka; Frączek, Ewa; Frączek, Wojciech ...
Optics express,
07/2022, Letnik:
30, Številka:
14
Journal Article
Recenzirano
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Remote positioning by precise measurements of lateral displacements of laser beams at large distances is inevitably disturbed by the influence of atmospheric turbulences. Here we propose the use of ...optical vortices, which exhibit lower transversal variations at an experimentally validated range of 100 meters. We show the higher precision of the localization of vortex points as compared with standard centroid-based assessment of Gaussian beams. Numerical simulations and experimental measurements show further improvements by averaging of the positions of up to four secondary vortices forming a stable constellation when higher values of the topological charges are used.
Off-axis projection is a common practice for reconstructions of Fourier holograms displayed on liquid crystal on silicon (LCoS) spatial light modulators (SLMs), as it spatially separates the image ...from the undiffracted light. Binary gratings encoded within the holograms enable maximum angular separation. However, as a result, two mirror images of equal intensities are present in the reconstruction. To introduce asymmetry to the intensity distribution and suppress one of those images, we propose a phase mask with a subpixel pattern. Presented results prove the potential of in-built SLM phase-mask layers for optimizing efficiency of the off-axis holographic projection.
We developed a passive silica based large mode area fiber with the nanostructured core with a diameter of 30 μm devoted to fiber Bragg grating inscription for application in an all-fiber laser ...cavity. The fiber is perfectly matched to the commercial active fiber with NA = 0.06 and core/cladding diameters 30/250 μm. Measured modal characteristics and bending loss of the fiber confirm single-mode operation for bending diameter of 8 cm with bending losses as low as 0.15 dB/m. Although the nanostructured fiber core is low germanium doped, we fabricated high reflectivity (98.5%) UV induced fiber Bragg grating (FBG) and verified its performance in fiber laser setup. The laser cavity formed with highly reflective FBG inscribed in the fiber and Fresnel reflection on the free end of active fiber results in lasing efficiency of 65.5%. The flexibility of the nanostructuring approach gives prospects for the development of free-form large mode area fibers for passive fiber components and matched with any type of active fibers.
•Extended depth of focus of imaging with high-end lenses equipped with static, transparent phase masks clipped on the objective.•Achromatic use of sparse diffractive optical element for broadband ...imaging.•Hollow-center, annular design of the phase filters allows unobstructed native quality of the lenses.•Easy experimental assessment of imaging quality by measurement of readability of alphanumerical symbols with a neural-network based algorithm.
In modern machine vision systems high-end lens objectives allow superior imaging on state-of-the-art sensor arrays due to highly corrected optical aberrations and large apertures. The resultant shallow depth of focus is a disadvantage, usually leading to programmatic attempts of extending it, with compromised image resolution. Here we present a simple optical system equipped with novel, annular peripheral add-on diffractive elements, allowing highly extended range of sharp imaging without any pre- or post-processing. The separation of main refractive focusing power from the proposed filters enables sparse kinoform zones leading to easy manufacturing and negligibly low chromaticity in polychromatic imaging. The undisturbed central region of the refractive objective sustains the full native imaging quality of the test Zeiss Otus lens. Convergent numerical and experimental results are presented, showing improved readability of alphanumerical symbols in a wide range of w20 defocus parameters up to 24 wavelengths. Robust neural network-based method of image quality assessment is also proposed based on statistical optical character recognition, allowing high dynamics and easy implementation in experimental use as compared to established methods.
Adherence to medications presents a significant challenge in healthcare. Statins, used in primary and secondary prevention of cardiovascular disease, are of particular importance for public health. ...The outbreak of the COVID-19 pandemic resulted in additional healthcare system-related barriers impeding the execution of therapies. This study aimed to assess the use of as well as adherence and persistence to statins in a national cohort of 38 million of Polish citizens during pandemic.
A retrospective analysis of prescription and dispensation data for all statins users from the national payer organization covering the years 2020-2022 was conducted. Medication adherence was assessed using the Medication Possession Ratio, for persistence the 30-day cut-off was accepted. National data on COVID-19 cases and COVID-19 related deaths were obtained from ECDC.
The analysis identified 7,189,716 Polish citizens (approximately 19% of Polish population) who were dispensed at least 1 pack of statins within the study period. Over that time, there was a continuous significant increasing trend in prescribing and dispensing of statins. Despite a total increase of 18.9% in the number of prescribed tablets, the percentage of tablets dispensed remained similar, averaging 86%. Overall percentage of adherent patients was 48.2%. For a random sample of 100,000 patients, the mean period of continuous therapy in 2022 was 6.2+/- 5.3 months. During the lockdown period, the mean number of prescribed and dispensed tablets was lower by 6.8% and 5.9%, respectively (
< 0.05). However, fluctuations in the number of COVID-19 cases or COVID-19-related deaths per week had no major impact on the prescribing and dispensing of statins.
Over the time of pandemic, there was a continuous increase in the number of statin tablets prescribed and dispensed in Poland. This suggests that, despite the potential limitations posed by COVID-19, access to statins remained easy, which may be attributed to the mass-scale implementation of the national e-prescription system. However, it is crucial to realise that approximately 1/7 of prescribed statin doses were never dispensed, and the overall levels of adherence and persistence were low. This underscores the necessity for concerted efforts to change this scenario in Poland.
Background : The Mayo Score MS, endoscopic Mayo Score eMS and the Ulcerative Colitis Index of Severity UCEIS are employed in the assessment of ulcerative colitis UC severity. This study compared the ...aforementioned indices in terms of predictory value for response to remission induction treatment with anti-TNF and anti-integrin biologics. Methods : A total of 38 patients were retrospectively evaluated in the study, 23 male and 15 female, aged 18–74 years old who had undergone a total of 53 biological therapy courses with either infliximab IFX or vedolizumab VDZ at the Department of Gastroenterology of the Medical University of Łódź. The clinical and endoscopic activity of UC was assessed at the outset of biological therapy and the 14th week remission induction assessment juncture. Results : The study analyzed 19 IFX and 34 VDZ treatment courses. The response rate of patients receiving IFX reached 73.67% and the response rate was 58.82% for VDZ. The mean MS, eMS and UCEIS improved among all patient groups: 8.316 ± 1.974 to 4.158 ± 2.218 (p < 0.05), 2.632 ± 0.597 to 1.790 ± 0.713 (p < 0.05) and 4.790 ± 1.745 to 3.000 ± 1.453 (p < 0.05) for IFX, 7.088 ± 2.234 to 3.618 ± 2.412 (p < 0.05), 2.706 ± 0.524 to 1.677 ± 1.065 (p < 0.05) and 4.235 ± 1.350 to 2.735 ± 1.880 (p < 0.05) for VDZ. Conclusions : The outcome assessment in induction treatment of UC includes clinical data and endoscopic evaluation. Severity of inflammatory lesion activity according to the eMS and UCEIS indices correlates with the overall disease presentation as evaluated with MS. The UCEIS provides an overall better predictor for biological induction treatment when compared with the eMS in both patient groups, particularly in those receiving VDZ. It provides a promising alternative to the eMS and can be employed for both initial disease severity assessment as well as for treatment response monitoring.
TrkB is a tyrosine kinase receptor that is activated upon binding to brain-derived neurotrophic factor (BDNF). To date, the search for low-molecular-weight molecules mimicking BDNF’s action has been ...unsuccessful. Several molecules exerting antidepressive effects in vivo, such as 7,8-DHF, have been suggested to be TrkB agonists. However, more recent publications question this hypothesis. In this study, we developed a set of experimental procedures including the evaluation of direct interactions, dimerization, downstream signaling, and cytoprotection in parallel with physicochemical and ADME methods to verify the pharmacology of 7,8-DHF and other potential reference compounds, and perform screening for novel TrkB agonists. 7,8 DHF bound to TrkB with Kd = 1.3 μM; however, we were not able to observe any other activity against the TrkB receptor in SN56 T48 and differentiated SH-SY5Y cell lines. Moreover, the pharmacokinetic and pharmacodynamic effects of 7,8-DHF at doses of 1 and 50 mg/kg were examined in mice after i.v and oral administration, respectively. The poor pharmacokinetic properties and lack of observed activation of TrkB-dependent signaling in the brain confirmed that 7,8-DHF is not a relevant tool for studying TrkB activation in vivo. The binding profile for 133 molecular targets revealed a significant lack of selectivity of 7,8-DHF, suggesting a distinct functional profile independent of interaction with TrkB. Additionally, a compound library was screened in search of novel low-molecular-weight orthosteric TrkB agonists; however, we were not able to identify reliable drug candidates. Our results suggest that published reference compounds including 7,8-DHF do not activate TrkB, consistent with canonical dogma, which indicates that the reported pharmacological activity of these compounds should be interpreted carefully in a broad functional context.
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