Experimental investigation in nodal aberration theory (NAT): separation of astigmatic figure error from misalignments in a Cassegrain telescope.

We present simulations and experimental validations for separating astigmatic figure error from misalignments in Nodal Aberration Theory (NAT) with a high-precision Cassegrain telescope. Both the primary mirror figure error and the secondary mirror misalignments induce binodal astigmatism for the telescope systems. The separation of these two aberration factors plays a crucial role in the telescope alignment process. In this study, the figure error of the aspheric primary mirror of the Cassegrain telescope induced by the mirror mounts was measured interferometrically utilizing a computer-generated hologram (CGH). According to the primary mirror figure error, the astigmatic node locations in the image plane were simulated using real raytracing. The center of the nodes was located on the field center, and the nodes were placed symmetrically with respect to the field center in the image plane. The telescope's alignment was performed using the simulation results, and the node locations were measured on a grid of field points interferometrically. Thereafter, secondary mirror misalignments around the coma-free pivot point were introduced into the optical system, and the node's center was shifted from the field center in the image plane as predicted by NAT. The simulations and interferometric field measurements were performed and compared on a grid of field points for the misaligned state in the presence of primary mirror figure error. The experimental results confirm the predictions from NAT. Statistical analysis was also performed to confirm the accuracy and stability of the measurements.

Several Tick-Borne Pathogenic Viruses in Circulation in Anatolia, Turkey.

Introduction: We screened host-collected ticks for tick-borne viruses, including those recently documented as human pathogens. Methods: During 2020-2021, ticks removed form cattle, sheep, dogs, and cats in 11 provinces in 5 geographically distinct regions of Anatolia were identified, pooled, and screened using pan-nairovirus, pan-flavivirus and individual assays for Jingmen tick virus (JMTV), and Tacheng tick virus 1 and 2 (TcTV-1 and TcTV-2). Results: A total of 901 tick specimens, comprising 6 species were included. Rhipicephalus sanguineus complex was the most abundant species (44.1%), followed by Rhipicephalus bursa (38.3%), Haemaphysalis parva (7.2%), and others. The specimens were screened in 158 pools with 12 pools (7.6%) being positive. Crimean-Congo hemorrhagic fever virus (CCHFV) lineage Europe 2 (genotype VI) sequences were detected in R. bursa in five (3.2%) of the pools, with similar prevalences in central and Mediterranean Anatolian provinces. JMTV was identified in four R. bursa and one Rhipicephalus turanicus pools, collected from Mediterranean and southeastern Anatolia, with a CCHFV and JMTV coinfected R. bursa pool. The JMTV segment 1 sequences formed a separate cluster with those from Turkey and the Balkan peninsula in the maximum likelihood analysis. TcTV-2 was detected in two Dermacentor marginatus specimens (1.3%) collected in central Anatolia, with nucleocapsid sequences forming a phylogenetically segregated group among viruses from humans and ticks from China and Kazakhstan. Discussion: CCHFV Europe 2 was initially documented in ticks from central Anatolian locations, where related orthonairoviruses had been previously recorded. Ongoing activity and a wider distribution of JMTV and TcTV-2 were observed. These viruses should be screened as potential etiological agents in human infections associated with tick bites.

Experimental investigation of binodal astigmatism in nodal aberration theory (NAT) with a Cassegrain telescope system.

We present simulations and an experimental investigation of binodal astigmatism in nodal aberration theory (NAT) for a customized, high-precision Cassegrain telescope system. The telescope system utilizes a five-axis, piezo-actuated flexural mechanism to introduce secondary mirror misalignments and generate aberrations intentionally. The induced aberrations are measured interferometrically and quantified for a grid of field points on the telescope system's image plane. For this purpose, a coma-free pivot point of the secondary mirror was simulated for isolating the binodal astigmatism field response. The separation of the nodes is proportional to the introduced misalignments. A simulation of Fringe Zernike coma and binodal astigmatism was generated using a real ray trace model of the optical system and analyzed to compare to the experimental results. A statistical analysis of the measurements was performed to show the experimental results' accuracy and stability. The experimental results were consistent with the simulations, hence experimentally validating NAT for binodal astigmatism for the first time.

Design of a high-precision, 0.5 m aperture Cassegrain collimator.

We present the realization of a high-precision, 0.5 m aperture size Cassegrain collimator system. The optical design, the optomechanical design, the mirror manufacturing, and the telescope alignment with a performance evaluation are extensively discussed. The optical design of the collimator is based on the Cassegrain telescope design with two aspheric mirrors. An athermalized, high stability optomechanical structure is conceived for the collimator to meet stringent performance requirements. The high-quality mirrors are made of low-expansion Zerodur glass-ceramic and the primary mirror is light-weighted to 63% of its initial weight. The design of a dedicated five-axis flexure mechanism driven by nanopositioner stages to compensate the secondary mirror misalignments is given. Primary and secondary mirrors with aspheric surfaces are manufactured, and their forms are measured by computer-generated holograms with a phase-shifting Fizeau interferometer. The alignment strategy is based on minimizing Fringe Zernike coefficients of wavefront decomposition measured by an autocollimation test setup. The alignment sensitivity and corresponding Fringe Zernike coefficient terms are determined by the ray-tracing software that introduces the intentional misalignments of the secondary mirror. The on-axis alignment of the collimator is performed with the guidance of sensitivity analysis results. The final root-mean-square wavefront error for the collimated beam is measured to be 0.021λ.

Thermal refocusing method for spaceborne high-resolution optical imagers.

We describe the design of a thermal refocusing method for spaceborne high-resolution imagers where Korsch optical design is usually implemented. The secondary mirror is made of aluminum, a high thermal expansion coefficient material, instead of conventional zero-expansion glass ceramics. In this way, the radius of the curvature can be controlled by means of temperature change of the mirror. Change in the radius of curvature also changes the effective focal length of the camera which is used for compensation of the defocus that occurred in space. We show that the 30 µm despace of the secondary mirror in the optical system can be compensated by an ∼10°C temperature change of the mirror while the image quality is maintained.

Malnutrition in Community-Dwelling Elderly in Turkey: A Multicenter, Cross-Sectional Study.

BACKGROUND: This study aimed to investigate the prevalence of malnutrition and explore the somatic, psychological, functional, and social or lifestyle characteristics linked to malnutrition in elderly people at a hospital in Turkey. MATERIAL AND METHODS: This study included 1030 patients older than 65 years of age who were seen at the internal medicine and geriatrics outpatient clinics of the study centers in Istanbul, Ankara, Duzce, Corum, Mardin, Malatya, and Diyarbakir provinces between January and December 2014. All patients underwent Mini Nutritional Assessment (MNA) and Geriatric Depression Scale (GDS) tests via one-on-one interview method. The demographic properties of the patients were also recorded during this interview. RESULTS: Among 1030 patients included in this study, 196 (19%) had malnutrition and 300 (29.1%) had malnutrition risk. The malnutrition group and the other groups were significantly different with respect to mean GDS score, income status, educational status, the number of children, functional status (ADL, IADL), the number of patients with depression, and the number of comorbid disorders. According to the results of the logistic regression analysis, age (OR=95% CI: 1.007-1.056; p=0.012), BMI (OR=95% CI: 0.702-0.796; p<0.001), educational status (OR=95% CI: 0.359-0.897; p=0.015), comorbidity (OR=95% CI: 2.296-5.448; p<0.001), and depression score (OR=95% CI: 1.104-3.051; p=0.02) were independently associated with malnutrition. CONCLUSIONS: Our study demonstrates that age, depression, BMI, comorbidity, and the educational status were independently associated with malnutrition in an elderly population.

What is the fate of clubfoot patients treated by posteromedial release?

INTRODUCTION: Management and long-term results of operatively treated clubfoot deformity still remains controversial. The aim of this study was to evaluate the radiological and clinical results of adult clubfoot patients treated with posteromedial release. MATERIALS AND METHODS: Between 2005 and 2012, we evaluated patients with congenital foot deformities regarding clubfoot who were operatively treated with complete posteromedial release. Out of 320 patients evaluated, 29 patients (40 feet) were included the study. We also included foot radiographies of 40 healthy adults. Talocalcaneal angle on the dorsoplantar projection (TC-DP) and lateral projection (TC-L) and talus-first metatarsal angle on the dorsoplantar projection (TFM-DP) were measured for both clubfeet and control groups. Laaveg-Ponseti functional rating system was used for clinical evaluation and measurement of lower leg circumference was used for detection of atrophy. RESULTS: The average age was 21.5 years (range 19-34). The mean TC-DP angle was 16.97 in the clubfeet group and 21.03 in the control group. The mean TC-L angle was 23.34 in the clubfeet group and 33.98 in the control group. The mean TFM-DP angle was 9.02 in the clubfeet group and 7.9 in control group. There were statistically significant difference between clubfoot and control groups regarding the TC-DP angle and the TC-L angle. The average Laaveg-Ponseti score was 74 points (range 42-96). While no significant correlations could be detected between the TC-DP angle, the TC-L angle, the TFM-DP angle and the functional score, a significant correlation was detected between circumferential measurement of lower leg and functional score (p = 0.04). CONCLUSION: Functional outcome may be affected by lower leg muscular atrophy instead of foot alignment disturbance. Lastly we believe that results for treatment of clubfoot-a three-dimensional deformity-need to be evaluated with three-dimensional imaging techniques.