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In order to achieve a nanometer-scale resolution in an x-ray microscopy system, a Gabor-type hologram was produced by eliminating the zero-order term of the object diffraction pattern. In this system, a Fresnel zone plate was used for strong illumination of an object, and the zero-order diffraction was physically eliminated by a center stop. An accurate phase plate of π/2 in the Zernike method was numerically created, and the phase-contrast image was realized. The theoretical resolution was 19.8 nm. We proved that a gold nanocube with a size of 50 nm can be reconstructed with the predicted resolution.

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OBJECTIVE: To compare the effects of eccentric muscle energy technique versus static stretching exercises combined with cervical segmental mobilisation in the management of upper cross syndrome in patients having neck pain. METHODS: The randomised controlled trial was conducted at the Khan Kinetic Treatment Canada Orthopaedic and Rehabilitation Centre, Rawalpindi, Pakistan, from August 2017 to January 2018, and comprised patients of upper cross syndrome who were randomized into two equal groups using lottery method. Patients in Group-A were treated with eccentric muscle energy technique with cervical segmental mobilisation, while those in Group-B received static stretching exercises with cervical segmental mobilisation. Two sessions per week for 3 weeks were given to each patient who were analysed by measuring tragus-to-wall distance, visual analogue scale and neck disability index. Cervical passive range of motion was measured using inclinometer. Data was recorded at baseline and after 3 weeks of treatment. Data was analysed using SPSS 21. RESULTS: Of the 40 subjects, 20(50%) each were in the two groups. In Group-A mean age was 42.75±11.13 years. In Group-B, it was 40.50±9.14 years. Eccentric muscle energy technique and static stretching technique both showed significant results (p<0.05) for within group analysis, but comparison across groups showed non-significant results (p>0.05 each) on all parameters. CONCLUSIONS: Both the techniques used were found to be equally effective in decreasing pain, improving cervical range of motion and reducing neck disability.

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Diffraction gratings are among the most commonly used optical elements in applications ranging from spectroscopy and metrology to lasers. Numerous methods have been adopted for the fabrication of gratings, including microelectromechanical system (MEMS) fabrication which is by now mature and presents opportunities for tunable gratings through inclusion of an actuation mechanism. We have designed, modeled, fabricated and tested a silicon based pitch tunable diffraction grating (PTG) with relatively large resolving power that could be deployed in a spaceborne imaging spectrometer, for example in a picosatellite. We have carried out a detailed analytical modeling of PTG, based on a mass spring system. The device has an effective fill factor of 52% and resolving power of 84. Tuning provided by electrostatic actuation results in a displacement of 2.7 µ m at 40 V . Further, we have carried out vibration testing of the fabricated structure to evaluate its feasibility for spaceborne instruments.

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Integral field spectroscopy (IFS) is a well-established method for measuring spectral intensity data of the form s(x,y,λ), where x, y are spatial coordinates and λ is the wavelength. In most flavors of IFS, there is a trade-off between sampling (x,y) and the measured wavelength band Δλ. Here we present the first, to our knowledge, attempt to overcome this trade-off by use of computational imaging and measurement diversity. We implement diversity by including a grating in our design, which allows rotation of the dispersed spectra between measurements. The raw intensity data captured from the rotated grating positions are then processed by an inverse algorithm that utilizes sparsity in the data. We present simulated results from spatial-spectral data in the experimental dataset. We used non-overlapping portions of the dataset to train our sparsity priors in the form of the dictionary, and to test the reconstruction quality. We found that, depending on the level of noise in the measurement, diversity up to a maximum number of measurements is beneficial in terms of reducing error, and yields diminishing returns if even more measurements are taken.

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Background & objectives: Pioglitazone was suspended for manufacture and sale by the Indian drug regulator in June 2013 due to its association with urinary bladder carcinoma, which was revoked within a short period (July 2013). The present questionnaire-based nationwide study was conducted to assess its impact on prescribing behaviour of physicians in India. Methods: Between December 2013 and March 2014, a validated questionnaire was administered to physicians practicing diabetes across 25 centres in India. Seven hundred and forty questionnaires fulfilling the minimum quality criteria were included in the final analysis. Results: Four hundred and sixteen (56.2%) physicians prescribed pioglitazone. Of these, 281 used it in less than the recommended dose of 15 mg/day. Most physicians (94.3%) were aware of recent regulatory events. However, only 333 (44.8%) changed their prescribing pattern. Seventeen of the 416 (4.1%) physicians who prescribed pioglitazone admitted having come across at least one type 2 diabetes mellitus patient (T2DM) who had urinary bladder carcinoma, and of these 13 said that it was in patients who took pioglitazone for a duration of more than two years. Only 7.8 per cent of physicians (n=58) categorically advocated banning pioglitazone, and the rest opined for its continuation or generating more evidence before decision could be taken regarding its use in T2DM. Interpretation & conclusions: Majority of the physicians though were aware of the regulatory changes with regard to pioglitazone, but their prescribing patterns were not changed for this drug. However, it was being used at lower than the recommended dose. There is a need for generating more evidence through improved pharmacovigilance activities and large-scale population-based prospective studies regarding the safety issues of pioglitazone, so as to make effectual risk-benefit analysis for its continual use in T2DM.

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In this paper, we show how the starlet transform can be used to process holograms from a digital Gabor holographic microscope. The starlet transform is an undecimated wavelet transform with the property that when performing reconstruction, we only need to add all scales without the use of a synthesis filter bank. When the starlet transform is applied to a hologram, we divide the hologram into a certain number of scales, process them separately, and propagate each one using a numerical diffraction method. After diffraction propagation, we perform processing on complex amplitudes that correspond to individual scales. With the aforementioned procedure, it is possible to reduce the background and effects of parasitic fringes caused by high coherence of a laser, enhance the contrast, and reduce the effects of the twin image. Experimental results confirming the method are presented.

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We use compressive in-line holography to image air bubbles in water and investigate the effect of bubble concentration on reconstruction performance by simulation. Our forward model treats bubbles as finite spheres and uses Mie scattering to compute the scattered field in a physically rigorous manner. Although no simple analytical bounds on maximum concentration can be derived within the classical compressed sensing framework due to the complexity of the forward model, the receiver operating characteristic (ROC) curves in our simulation provide an empirical concentration bound for accurate bubble detection by compressive holography at different noise levels, resulting in a maximum tolerable concentration much higher than the traditional back-propagation method.

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We propose a new approach to the complete retrieval of a coherent field (amplitude and phase) using the same hardware configuration as a Shack-Hartmann sensor but with two modifications: first, we add a transversally shifted measurement to resolve ambiguities in the measured phase; and second, we employ factored form descent (FFD), an inverse algorithm for coherence retrieval, with a hard rank constraint. We verified the proposed approach using both numerical simulations and experiments.

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Optical coherence tomography (OCT) is a widely used structural imaging method. However, it has limited use in molecular imaging due to the lack of an effective contrast mechanism. Gold nanoparticles have been widely used as molecular probes for optical microcopy based on Surface Plasmon Resonance (SPR). Unfortunately, the SPR enhanced backscattering from nanoparticles is still relatively weak compared with the background signal from microscopic structures in biological tissues when imaged with OCT. Consequently, it is extremely challenging to perform OCT imaging of conventional nanoparticles in thick tissues with sensitivity comparable to that of fluorescence imaging. We have discovered and demonstrated a novel approach towards remarkable contrast enhancement, which is achieved by the use of a circular-polarization optical coherence microscopy system and 3-dimensional chiral nanostructures as contrast agents. By detecting the circular intensity differential depolarization (CIDD), we successfully acquired high quality images of single chiral nanoparticles underneath a 1-mm-thick tissue -mimicking phantom.

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Focal modulation microscopy (FMM) has been demonstrated more effective than confocal microscopy for imaging of thick biological tissues. To improve its penetration depth further, we propose a simple analytical method to enlarge the modulation depth, the unique property of FMM directly linked to its signal-to-noise ratio. The modulation depth increases as the excitation intensity of the binary phase aperture status is pushed further away from the focal region of the detection optics, thereby creating a dark region in the focal volume, which we call maximally flat crater (MFC). By direct algebraic manipulation, MFCs are achieved for both scalar and vector diffraction optics. Numerical results show that the modulation depth from MFC is very close to the maximum values, with a small difference less than 3% for the same number of subapertures. Applications of bifocus produced by MFC apertures are also discussed.

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: We propose a scheme based on extraordinary transmission of light through a single nanoaperture, surrounded by periodic corrugations, for direct characterization of focal-region optical fields with subwavelength-scale structure. We describe the design of the device on the basis of rigorous diffraction theory and fabricate a prototype using a process that involves electron beam lithography, dry etching, and template stripping. First experimental results performed with a transmission-type confocal optical microscope demonstrate the potential of the method.

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We formulate coherence retrieval, the process of recovering via intensity measurements the two-point correlation function of a partially coherent field, as a convex weighted least-squares problem and show that it can be solved with a novel iterated descent algorithm using a coherent-modes factorization of the mutual intensity. This algorithm is more memory-efficient than the standard interior point methods used to solve convex problems, and we verify its feasibility by reconstructing the mutual intensity of a Schell-model source from both simulated data and experimental measurements.

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Optical microscopy has been widely applied in cellular and subcellular imaging. Conventional light microscopes, however, have rather limited imaging depth and are limited to imaging only mechanically sectioned thin samples. Multiphoton microscopy and optical coherence microscopy are common techniques for diffraction-limited imaging beyond an imaging depth of 0.5 mm. Focal modulation microscopy is a novel method that combines confocal spatial filtering with focal modulation to reject out-of-focus backgrounds. Focal modulation microscopy has demonstrated an imaging depth comparable to those of multiphoton microscopy and optical coherence microscopy, near-real-time image acquisition, and capability with a multiple contrast mechanism.

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The idea of superresolving pupil filters comes from the concept of superoscillations that may occur in regions of a band-limited signal with small amplitude having oscillations faster than the fastest Fourier component of the signal. In optical microscopy, superresolution can be achieved by appropriate design of pupil functions where the angular aperture determines the ultimate focal spot smaller than the Abbe diffraction limit outside the evanescent field region. The angular aperture cannot be increased indefinitely and the huge sidelobes cannot be avoided that are present in superresolving filters. The limitations of using such kind of filters in microscopy applications are discussed through computational examples.

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Focusing properties of transverse circular polarization modes that bring light to a small focal spot are investigated. Two particular illumination polarization distributions are discussed. Rotating electric dipole polarization results in a central lobe diameter 8% smaller than for the circularly polarized aplanatic case at a NA of 0.95 in air and is also smaller than for radial polarization at NAs less than 0.90. Azimuthal polarization with a phase singularity of charge unity results in a small central lobe width that is smaller than that produced by focusing radially polarized light, having a width that is 17% smaller than for circularly polarized illumination at a NA of 0.95.

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Fluorescence, absorption and vibrational spectroscopic techniques were used to study spinach at the photosystem II (PS II), chloroplast and cellular levels and to determine the effects and mechanisms of ultraviolet-B (UV-B) photoinhibition of these structures. Two-photon fluorescence spectroscopic imaging of intact chloroplasts shows significant spatial variations in the component fluorescence spectra in the range 640-740 nm, indicating that the type and distribution of chlorophylls vary markedly with position in the chloroplast. The chlorophyll distributions and excitonic behaviour in chloroplasts and whole plant tissue were studied using picosecond time-gated fluorescence imaging, which also showed UV-induced kinetic changes that clearly indicate that UV-B induces both structural and excitonic uncoupling of chlorophylls within the light-harvesting complexes. Transient absorption measurements and low-frequency infrared and Raman spectroscopy show that the predominant sites of UV-B damage in PS II are at the oxygen-evolving centre (OEC) itself, as well as at specific locations near the OEC-binding sites.

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