Enhanced transmission through a subwavelength aperture using metamaterials

We report an enhanced transmission through a single circular subwavelength aperture that is incorporated with a split ring resonator (SRR) at the microwave regime. Transmission enhancement factors as high as 530 were observed in the experiments when the SRR was located in front of the aperture in order to efficiently couple the electric field component of the incident electromagnetic wave at SRR's electrical resonance frequency. The experimental results were supported by numerical analyses. The physical origin of the transmission enhancement phenomenon was discussed by examining the induced surface currents on the structures

Photonic crystal based sensing using band edge modulation

A photonic crystal based structure is proposed for sensing exceptionally small refractive index changes of a background medium. In a typical photonic crystal, we show that the band edges and the defect band(s) (if present) are very sensitive to the dielectric contrast. Hence, a propagating electromagnetic wave at a particular frequency gains significant phase shift due to the index changes. When the phase shift is measured interferometrically, it is possible to infer refractive index changes as small as 10⁻¹¹ per lattice distance. We have mainly concentrated on the band edge shifts of the two lowest bands of a square lattice of dielectric rods. Calculations reveal that an optimized design of 100x100 rods could be utilized to sense an index modulation of ten to the power minus thirteen per square roots Hertz with a modulation bandwidth of 1 Hz, which is approximately 10⁵ times better than the resolution of novel waveguide based sensor configurations. We also report that defect modes in photonic crystals are even better candidates to be adapted for sensing applications. A further resolution enhancement on the order of 10 could be achived due to the high sensitivity of the defect bands. We have performed proof of principle experiments in the microwave regime with a photonic crystal wave of 7x7 alumina rods placed in a gas chamber, whose inner pressure can be adjusted with a nitrogen tank. Obtaining the index modulations by changing the inner pressure, we witnessed that the experimental results are in very good argeement with the theory at the band adges

A Randomised Control Trial and Comparative Analysis of Multi-Dimensional Learning Tools in Anatomy

Research was funded by the Cakmak Lab and the University of Otago, Otago Medical School. Author notes: These authors contributed equally: Ben Kei Daniel and Mustafa Asil. Contributions: Conception and Design of Study: Y.C. and C.W.; Design of materials: Y.C. and C.W.; Randomization of participants: P.K.; Acquisition of data: C.W.; Data analysis and interpretation: Y.C., M.A., B.D. and C.W.; Drafting of manuscript and/or critical revision: C.W., Y.C., M.A., B.D. and P.K.; All authors read and approved the final manuscript.Peer reviewedPublisher PD

Serum Copeptin Levels in Adult Patients with a Migraine Attack: A Cross-Sectional Study

Aim:This study investigated the potential role of serum copeptin, a mediator of acute pain via sympathetic stress stimulation, as a biomarker of varying degrees of migraine-related disability. Specifically, we aimed to analyze whether the serum copeptin level can be used to differentiate migraine types (e.g., with and without aura).Methods:The study population included 80 consecutively consenting adult patients who had migraine attacks and attended the emergency department from June 2020 through November 2020, as well as 80 age- and sex-matched healthy controls. Using the Migraine Disability Assessment Scale (MIDAS), the same medical professional assessed each patient’s level of headache-related disability. Based on their MIDAS scores, the patients were separated into four groups: no disability (score 0-5; group MIDAS-I); mild disability (score 6-10; group MIDAS-II); moderate impairment (score 11-20; group MIDAS-III); and severe disability (score >20; group MIDAS-IV). There were also two categories of migraineurs: those with auras and those without auras. Upon admission, comparisons were made between the groups’ serum copeptin values.Results:In comparison to the control group, the patient group’s serum copeptin levels were noticeably higher (2113.30±206.20 vs. 1383.40±488.40; p<0.001). The study of the receiving operator’s characteristics showed that the cut-off copeptin level was 1898.5 pg/mL, with 90% sensitivity and 82.4% specificity for distinguishing patients from controls. There were no noticeable differences in the mean serum copeptin levels between the patient groups when compared by MIDAS score. Additionally, patients with and without aura did not differ notably in terms of mean serum copeptin levels. (2118.70±211.60 vs. 2071.10±160.40).Conclusion:Serum copeptin levels may be used as a diagnostic aid to help anticipate migraine-related headache attacks when combined with clinical signs and symptoms

Glyphosate inhibition of ferric reductase activity in iron deficient sunflower roots

Iron (Fe) deficiency is increasingly being observed in cropping systems with frequent glyphosate applications. A likely reason for this is that glyphosate interferes with root uptake of Fe by inhibiting ferric reductase in roots required for Fe acquisition by dicot and nongrass species. This study investigated the role of drift rates of glyphosate (0.32, 0.95 or 1.89 mM glyphosate corresponding to 1, 3 and 6% of the recommended herbicidal dose, respectively) on ferric reductase activity of sunflower (Helianthus annuus) roots grown under Fe deficiency conditions. Application of 1.89 mM glyphosate resulted in almost 50% inhibition of ferric reductase within 6 h and complete inhibition 24 h after the treatment. Even at lower rates of glyphosate (e.g. 0.32 mM and 0.95 mM), ferric reductase was inhibited. Soluble sugar concentration and the NAD(P)H oxidizing capacity of apical roots were not decreased by the glyphosate applications. To our knowledge, this is the first study reporting the effects of glyphosate on ferric reductase activity. The nature of the inhibitory effect of glyphosate on ferric reductase could not be identified. Impaired ferric reductase could be a major reason for the increasingly observed Fe deficiency in cropping systems associated with widespread glyphosate usage

Case Report Transitional Cell Carcinoma in Orthotopic Ileal Neobladder

Urothelial carcinoma developing in orthotopic ileal neobladder is an extremely rare entity. Fewer than 10 cases have been reported in the literature describing urothelial carcinoma recurrence in orthotopic ileal neobladder. We report a case of transitional cell carcinoma recurrence in orthotopic ileal neobladder after 11 years of surgery

Split ring resonator-coupled enhanced transmission through a single subwavelength aperture

We report the enhanced transmission of electromagnetic waves through a single subwavelength aperture by making use of the resonance behavior of a split ring resonator (SRR) at microwave frequencies. By placing a single SRR at the near-field of the aperture, strongly localized electromagnetic fields are effectively coupled to the aperture with a radius that is twenty times smaller than the resonance wavelength. We obtained 740-fold transmission enhancement by exciting the electric resonance of SRR. A different coupling mechanism, through the magnetic resonance of SRR, is also verified to yield enhanced transmission. Good agreement is obtained between the microwave measurements and numerical simulations.Comment: 14 pages, 4 figures, to be submitted to PR