We examine experimentally the influence of the fiber inelastic twist on polarimetric sensitivity to hydrostatic pressure and pressure sensitivity in a Rayleigh-scattering-based optical ...frequency-domain reflectometer (OFDR) for highly birefringent side-hole fibers. The fibers were drawn from the same preform with different spin pitches varying from 5 mm to 200 mm. We also demonstrate that the sensitivities of spun fiber can be estimated analytically based on its spin pitch, measured birefringence, and the sensitivity of the corresponding non-twisted fiber, showing good agreement with the experimental results. We proved that polarimetric sensitivity to pressure decreases with the shorter spin pitches, while distributed pressure sensitivity decreases for the one polarization eigenmode and increases for the second polarization eigenmode. Therefore, the spun-fibers can operate well as the polarimetric sensors of other physical parameters inducing circular birefringence even under varying pressure. Moreover, they can be used to obtain the desired difference between sensitivities for both polarization eigenmodes
We present a rocking filter in a highly birefringent two-mode fiber that enables resonant coupling between different modes in the LP
group. Our simulations and experimental results prove that such a ...filter allows for resonant coupling between orthogonally polarized LP
modes of the same spatial structure, as well as between modes of the same polarizations and orthogonal spatial distributions. Furthermore, we demonstrate that such rocking filters can be used to generate pure TE
, TM
and HE
beams or their coherent superposition.
We demonstrate a fiber-based optical vortex beam source operating in broadband or tunable mode in the spectral range of 1100–1400 nm. The vector vortices of the total angular momenta equal to +2, 0, ...and −2 are obtained by converting the respective linearly polarized (LP
11
) modes of the two-mode birefringent PANDA fiber with stress-applying elements by gradually twisting its output section. At the input end, the PANDA fiber is powered by broadband supercontinuum or tunable Raman solitons generated in the LP
11
polarization modes of a birefringent microstructured fiber with a specially designed dispersion profile and coupled to the respective LP
11
modes of the PANDA fiber. Two pulse lasers operating in different regimes (1 ns/1064 nm and 190 fs/1037 nm) were used as the pump to generate supercontinuum or tunable solitons directly in the LP
11
modes of the microstructured fiber purely excited with a special Wollaston prism-based method. The high modal and polarization purities of the beams after successive transformations were experimentally confirmed. We also proved the vortex nature of the output beams using shearing interferometry.
Helical core fibers (HCFs) suffer from low coupling efficiency and unavoidable excitation of higher order modes below the cutoff wavelength because of a core tilt with respect to the symmetry axis of ...the cladding. We propose an effective way of increasing the coupling efficiency to a HCF by untwisting its beginning section in a hydrogen flame. The proposed solution provides also a control over the excitation of higher order modes in HCFs and can be applied in splicing as well as in a free-space launching configuration. We experimentally demonstrate that by using the proposed method, the coupling efficiency between a SMF-28 and HCF can be increased to the level reachable for straight fibers, which is limited only by a modal fields mismatch. We also present detailed numerical and analytical studies of the coupling efficiency between a HCF and SMF versus the pitch distance in the partially untwisted input section of the HCF, which takes into account fundamental and higher-order modes.
We report on a new phenomenon of light guidance in a fiber core created by an arrangement of holes making a partially open ring. In such structure there is no complete refractive index barrier to ...confine the light and therefore it cannot guide light if untwisted. However, if the open ring of holes is shifted off the symmetry axis of the twisted fiber then the mode confinement and low loss propagation is possible due to purely geometrical effect related to the increase in the optical path of light following the helical route. Properties of such structures, including confinement loss, modal field distribution, birefringence of fundamental modes were investigated both numerically and experimentally. We also studied the effect of bending, which leads to periodic modulation of the propagation characteristics of the twisted fiber. Furthermore, we demonstrate a possibility of displacement measurements based on bend-induced loss using some of the fabricated fibers, in which the sensitivity to bend is controlled by a twist rate and core structure.
W artykule została poruszona tematyka zmiany społecznej oraz wynikających z niej problemów. Opisane zostały zmiany, które w ostatnim czasie zaszły w społeczeństwie polskim. Wpływ na nie miały ...różne czynniki, np. polityczne – takie jak napływ uchodźców z Ukrainy do Polski, ekonomiczne – niskie bezrobocie lub demograficzne – starzenie się społeczeństwa. Przedstawiono badania własne autorki, która przeprowadziła je wśród pracowników i klientów pomocy społecznej. Określali oni poziom zapotrzebowania na różnego rodzaju usługi społeczne świadczone przez Ośrodek Pomocy Społecznej, a także pomogli w scharakteryzowaniu grup osób potrzebujących. W drugiej części artykułu podjęto dyskusje nad potrzebą stworzenia nowych narzędzi pracy socjalnej, które będą kompatybilne zarówno z potrzebami współczesnych odbiorców działań pomocowych, jak i ze zmieniającą się rzeczywistością społeczną Polski. W dyskusji tej zwrócono uwagę na standardy pracy socjalnej i narzędzi wypracowane przez WRZOS. Zaprezentowane zostały badania zlecone przez MOPS Uniwersytetowi Wrocławskiemu, w których to jednym z zadań było przygotowanie narzędzi pracy socjalnej do pracy z ofiarami przemocy domowej z Ukrainy. W związku z tym zaproponowano wytyczne, które powinny być wzięte pod uwagę w konstrukcji nowych narzędzi pracy socjalnej. Została również podkreślona rola pracownika socjalnego jako osoby, która czynnie powinna się włączać w pracę nad nowymi narzędziami pracy socjalnej, np. testować je, ulepszać, brać udział w zespołach merytorycznych.
Under physiological conditions skeletal muscle regeneration depends on the satellite cells. After injury these cells become activated, proliferate, and differentiate into myofibers reconstructing ...damaged tissue. Under pathological conditions satellite cells are not sufficient to support regeneration. For this reason, other cells are sought to be used in cell therapies, and different factors are tested as a tool to improve the regenerative potential of such cells. Many studies are conducted using animal cells, omitting the necessity to learn about human cells and compare them to animal ones. Here, we analyze and compare the impact of IL-4 and SDF-1, factors chosen by us on the basis of their ability to support myogenic differentiation and cell migration, at mouse and human adipose tissue-derived stromal cells (ADSCs). Importantly, we documented that mouse and human ADSCs differ in certain reactions to IL-4 and SDF-1. In general, the selected factors impacted transcriptome of ADSCs and improved migration and fusion ability of cells in vitro. In vivo, after transplantation into injured muscles, mouse ADSCs more eagerly participated in new myofiber formation than the human ones. However, regardless of the origin, ADSCs alleviated immune response and supported muscle reconstruction, and cytokine treatment enhanced these effects. Thus, we documented that the presence of ADSCs improves skeletal muscle regeneration and this influence could be increased by cell pretreatment with IL-4 and SDF-1.
Elderly patients pose a significant challenge to intensive care unit (ICU) clinicians. In this study we attempted to characterise the population of patients over 80 years old admitted to ICUs in ...Poland and identify associations between clinical features and short-term outcomes.
The study is a post-hoc analysis of the Polish cohort of the VIP2 European prospective observational study enrolling patients > 80 years old admitted to ICUs over a 6-month period. Data including clinical features, clinical frailty scale (CFS), geriatric scales, interventions within the ICU, and outcomes (30-day and ICU mortality and length of stay) were gathered. Univariate analyses comparing frail (CFS > 4) to non-frail patients and survivors to non-survivors were performed. Multivariable models with CFS, activities of daily living score (ADL), and the cognitive decline questionnaire IQCODE as predictors and ICU or 30-day mortality as outcomes were formed.
A total of 371 patients from 27 ICUs were enrolled. Frail patients had significantly higher ICU (58% vs. 44.45%, P = 0.03) and 30-day (65.61% vs. 54.14%, P = 0.01) mortality compared to non-frail counterparts. The survivors had significantly lower SOFA score, CFS, ADL, and IQCODE than non-survivors. In multivariable analysis CFS (OR 1.15, 95% CI: 1.00-1.34) and SOFA score (OR 1.29, 95% CI: 1.19-1.41) were identified as significant predictors for ICU mortality; however, CFS was not a predictor for 30-day mortality ( P = 0.07). No statistical significance was found for ADL, IQCODE, polypharmacy, or comorbidities.
We found a positive correlation between CFS and ICU mortality, which might point to the value of assessing the score for every patient admitted to the ICU. The older Polish ICU patients were characterised by higher mortality compared to the other European countries.
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