Frequency-Doubling of Femtosecond Pulses in “Thick” Nonlinear Crystals With Different Temporal and Spatial Walk-Off Parameters

We present a comparative study on frequency-doubling characteristics of femtosecond laser pulses in thick nonlinear crystals with different temporal and spatial walk-off parameters. Using single-pass second harmonic generation (SHG) of 260 fs pulses at 1064 nm from a high-average-power femtosecond Yb-fiber laser in 5-mm-long crystals of β-BaB2O4 (BBO) and BiB3O6 (BIBO), we find that for comparable values of temporal and spatial walk-off parameters in each crystal, the optimum focusing condition for SHG is more strongly influenced by spatial walk-off than temporal walk-off. It is also observed that under such conditions, the Boyd and Kleinman theory commonly used to define the optimum focusing condition for frequency-doubling of cw and long-pulse lasers is also valid for SHG of ultrafast lasers. We also investigate the effect of focusing on the spectral, temporal, and spatial characteristics of the second harmonic (SH) radiation, as well as angular acceptance bandwidth for the SHG process, under different temporal and spatial walk-off conditions in the two crystalsPeer ReviewedPostprint (author's final draft

Temperature-dependent proximity magnetism in Pt

We experimentally demonstrate the existence of magnetic coupling between two ferromagnets separated by a thin Pt layer. The coupling remains ferromagnetic regardless of the Pt thickness, and exhibits a significant dependence on temperature. Therefore, it cannot be explained by the established mechanisms of magnetic coupling across nonmagnetic spacers. We show that the experimental results are consistent with the presence of magnetism induced in Pt in proximity to ferromagnets, in direct analogy to the well-known proximity effects in superconductivity.Comment: 4 pages, 3 figure

Variability in gene cassette patterns of class 1 and 2 integrons associated with multi drug resistance patterns in Staphylococcus aureus clinical isolates in Tehran-Iran

Background: To investigate antibiotic resistance, the occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran. The isolates were examined for susceptibility to antimicrobial agents. The mecA gene, class 1 and 2 integrons were detected by PCR. Integrase positive strains were further analysed for the presence of resistance gene cassettes using specific primers and were sequenced. Results: Among 139S.aureus isolates, 109 (78.4 ) and 112 (80.5 ) strains were considered as multidrug resistant and mecA positive, respectively. Class 1 integrons and internal variable regions were found in 72.6 (101/139) and 97 (98/101) and class 2 integrons and variable regions also in 35.2 (49/139) and 65.3 (32/49) of S.aureus clinical isolates, respectively. Twelve distinct cassette arrays were found, containing genes encoding resistance to β-lactams, aminoglycosides, streptothricin, trimethoprim, chloramphenicol,a putative glucose dehydrogenase precursor and a protein with unknown function. Gene cassette arrays aadB, aadA2 and dhfrA1-sat2-aadA1 were common in S.aureus isolates. We detected a completely new gene cassettes which contained aadB, oxa2, aacA4, orfD-aacA4-catB8, aadB-catB3, orfD-aacA4 and aadB-aadA1-cmlA6 of class 1 and dhfrA1-sat2-aadA1, dhfrA11, dhfrA1-sat2 of class 2 integrons. Conclusions: This is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes among in S.aureus isolates from Iran. © 2015 Mostafa et al

Video-rate, mid-infrared hyperspectral upconversion imaging

This is the final version. Available from Optical Society of America via the DOI in this recordIn this work we demonstrate, to the best of our knowledge, a novel wide field-of-view upconversion system, supporting upconversion of monochromatic mid-infrared (mid-IR) images, e.g., for hyperspectral imaging (HSI). An optical parametric oscillator delivering 20 ps pulses tunable in the 2.3–4 μm range acts as a monochromatic mid-IR illumination source. A standard CCD camera, in synchronism with the crystal rotation of the upconversion system, acquires in only 2.5 ms the upconverted mid-IR images containing 64 kpixels, thereby eliminating the need for postprocessing. This approach is generic in nature and constitutes a major simplification in realizing video-frame-rate mid-IR monochromatic imaging. A second part of this paper includes a proof-of-principle study on esophageal tissues samples, from a tissue microarray, in the 3–4 μm wavelength range. The use of mid-IR HSI for investigation of esophageal cancers is particularly promising as it allows for a much faster and possibly more observer-independent workflow than state-of-the-art histology. Comparing histologically stained sections evaluated by a pathologist to images obtained by either Fourier transform IR or upconversion HSI based on machine learning shows great promise for further work pointing towards clinical translation using the presented mid-IR HSI upconversion system.European CommissionH2020 Marie Skłodowska-Curie ActionsMinisterio de Ciencia, Innovación y UniversidadesGeneralitat de CatalunyaEuropean Social Fun

From fuzzy to annotated semantic web languages

The aim of this chapter is to present a detailed, selfcontained and comprehensive account of the state of the art in representing and reasoning with fuzzy knowledge in Semantic Web Languages such as triple languages RDF/RDFS, conceptual languages of the OWL 2 family and rule languages. We further show how one may generalise them to so-called annotation domains, that cover also e.g. temporal and provenance extensions

Comparing Serum and 24-hour Urine Calcium between Preeclamptic and Non-preeclamptic Patients

Introduction: Preeclampsia is one of the most important complications of pregnancy which increases maternal morbidity and mortality. Calcium homeostasis disorders may have some roles in vascular hypersensitivity in preeclampsia. Therefore, the purpose of this study was to compare calcium of serum and 24-hour urine between preelamptic and normotensive pregnant patients. Methods: This is a descriptive-analytic study including 50 preeclamptic pregnant and 50 normotensive pregnant females attending to gynecologic and obstetrics ward of Imam Khomeini and Razi hospitals of Ahvaz in 2009. Calcium levels of serum and 24-hour urine were compared in the both groups. Then, liver enzymes, platelets, serum creatinine, and 24-hour urine protein were compared among preeclamtic patients. The results were statistically analyzed using SPSS software. Results: No statistically significant difference was found between serum calcium means in the two groups (p=0.07), though mean of 24-hour urine calcium in preeclamptic patients was significantly lower than that of control group (p=0.0003). In preeclamptic group, the degree of hypocalciuria was related to disordered liver enzymes, serum creatinine greater than 1.2 mg/dl, thrombocytopenia and proteinuria more than 2g/24h. Conclusion: Preeclampsia is associated with hypocalciuria; the more hypocalciuria there exists , the more preeclampsia is observed

Ultrafast optical vortex beam generation in the ultraviolet

We report on the generation of ultrafast vortex beams in the deep ultraviolet (DUV) wavelength range at 266 nm, for the first time to our knowledge. Using a Yb-fiber-based green source in combination with two spiral phase plates of orders 1 and 2, we were able to generate picosecond Laguerre–Gaussian (LG) beams at 532 nm. Subsequently, these LG beams were frequency doubled by single-pass, second-harmonic generation in a 10 mm-long \u1d6fd-BaB2O4β-BaB2O4 crystal to generate ultrafast vortex beams at 266 nm with a vortex order as high as 12, providing up to 383 mW of DUV power at a single-pass, green-to-DUV conversion efficiency of 5.2%. The generated picosecond UV vortex beam has a spectral width of 1.02 nm with a passive power stability better than 1.2% rms over >1.5  h>1.5  h.Peer Reviewe