Multifunctional meta-mirror: polarization splitting and focusing

Metasurfaces are paving the way to improve traditional optical components by integrating multiple functionalities into one optically flat metasurface design. We demonstrate the implementation of a multifunctional gap surface plasmon-based metasurface which, in reflection mode, splits orthogonal linear light polarizations and focuses into different focal spots. The fabricated configuration consists of 50 nm thick gold nanobricks with different lateral dimensions, organized in an array of 240 nm x 240 nm unit cells on the top of a 50 nm thick silicon dioxide layer, which is deposited on an optically thick reflecting gold substrate. Our device features high efficiency (up to ~65%) and polarization extinction ratio (up to ~30 dB), exhibiting broadband response in the near-infrared band (750-950 nm wavelength) with the focal length dependent on the wavelength of incident light. The proposed optical component can be forthrightly integrated into photonic circuits or fiber optic devices.Comment: 18 pages, including 5 figure

Prosthetic rehabilitation after enucleation of cystic lesion with semi precision attachment and telescopic crown

The demand for a quality dental practice is increasing in today’s era. Along with the form and function of the prosthesis, esthetics is also a matter of concern. Prosthetic rehabilitation of an enucleated cystic lesion becomes challenging in some conditions. Here, we report the case of prosthetic rehabilitation after enucleation of the cystic lesion with semi-precision attachment and telescopic crown in a 30-year-old female. In this case after enucleation of Odontogenic Keratocyst, the prosthesis was fabricated using semi-precision attachment along with the telescopic crown which provided proper retention, stability, and aesthetics.&nbsp

Prosthetic rehabilitation of an osteoporosis case with semi precision attachments and cast partial dentures - A case report

Osteoporosis is a skeletal disorder that has emerged as a major health problem affecting mostly in the postmenopausal women and older individuals. In osteoporosis, there is an imbalance between the bone formation and bone resorption where in, there is an increase in resorption. It even affects the jaw bones making a challenging task for the prosthetic rehabilitation. Here, we present a case report of prosthetic rehabilitation of an osteoporosis case of 65-year-old woman, using semi precision attachments with Cast partial dentures

Investigating the robustness of a learning-based method for quantitative phase retrieval from propagation-based x-ray phase contrast measurements under laboratory conditions

Quantitative phase retrieval (QPR) in propagation-based x-ray phase contrast imaging of heterogeneous and structurally complicated objects is challenging under laboratory conditions due to partial spatial coherence and polychromaticity. A learning-based method (LBM) provides a non-linear approach to this problem while not being constrained by restrictive assumptions about object properties and beam coherence. In this work, a LBM was assessed for its applicability under practical scenarios by evaluating its robustness and generalizability under typical experimental variations. Towards this end, an end-to-end LBM was employed for QPR under laboratory conditions and its robustness was investigated across various system and object conditions. The robustness of the method was tested via varying propagation distances and its generalizability with respect to object structure and experimental data was also tested. Although the LBM was stable under the studied variations, its successful deployment was found to be affected by choices pertaining to data pre-processing, network training considerations and system modeling. To our knowledge, we demonstrated for the first time, the potential applicability of an end-to-end learning-based quantitative phase retrieval method, trained on simulated data, to experimental propagation-based x-ray phase contrast measurements acquired under laboratory conditions. We considered conditions of polychromaticity, partial spatial coherence, and high noise levels, typical to laboratory conditions. This work further explored the robustness of this method to practical variations in propagation distances and object structure with the goal of assessing its potential for experimental use. Such an exploration of any LBM (irrespective of its network architecture) before practical deployment provides an understanding of its potential behavior under experimental settings.Comment: Under review as a journal submission. Early version with partial results has been accepted for poster presentation at SPIE-MI 202

AmbientFlow: Invertible generative models from incomplete, noisy measurements

Generative models have gained popularity for their potential applications in imaging science, such as image reconstruction, posterior sampling and data sharing. Flow-based generative models are particularly attractive due to their ability to tractably provide exact density estimates along with fast, inexpensive and diverse samples. Training such models, however, requires a large, high quality dataset of objects. In applications such as computed imaging, it is often difficult to acquire such data due to requirements such as long acquisition time or high radiation dose, while acquiring noisy or partially observed measurements of these objects is more feasible. In this work, we propose AmbientFlow, a framework for learning flow-based generative models directly from noisy and incomplete data. Using variational Bayesian methods, a novel framework for establishing flow-based generative models from noisy, incomplete data is proposed. Extensive numerical studies demonstrate the effectiveness of AmbientFlow in correctly learning the object distribution. The utility of AmbientFlow in a downstream inference task of image reconstruction is demonstrated

Efficacy, tolerability and safety of intravenous iron sucrose in postpartum anaemia

Background: Anemia is one of major contributing factor in maternal mortality and morbidity in third world countries and according to the WHO, contributes to 40% maternal deaths. Postpartum anemia is observed in up to 27% of women.It is a common problem throughout the world. Treatment of postpartum iron deficiency anemia includes oral and parenteral iron supplmentaion as well as blood transfusion in severe cases. Methods: This was a prospective longitudinal study carried out in Department of Obstetrics & Gynaecology of PRH, Loni. Total 80 women suffering from postpartum anemia of age above 18 years with haemoglobin (HB) level below 11gm/dl and above 6gm/dl were included for the study. After history taking, clinical examination and baseline Hb level, all of them were administered intravenous iron sucrose 200 mg per dose per day till the total calculated dose was administered. The post therapy evaluation was done with the estimation of Hb on day 1, day 7, day 14 and day 21. Results: 31.25% women belonged to the age group each of 19-21 years and 22-24 years. Maximum number of patients received 3 doses of IV Iron sucrose (i.e. total 600mg) followed by 2 doses (i.e. total 400mg), 4 doses (i.e. total 800mg) and 5 doses (i.e. total 1000mg) respectively. Hb level rises extremely significantly (p<0.001) after IV Iron Sucrose administration on day 1, 7, 14 & 21 as compared to corresponding values before delivery as analyzed by Friedman Test (Nonparametric Repeated Measures ANOVA) . 16 patients (20%) experienced thrombophlebitis to IV Iron Sucrose administration. About 12 (15%) patients experienced rigor followed by sweating in 10 patients (12.5%) and fever in 8 patients (10%). About 62 patients (77.5%) from total 80 reported well tolerability to IV Iron Sucrose while remaining 18 patients (22.5%) reported poor tolerability to IV Iron Sucrose Conclusion: Intravenous iron sucrose increases the haemoglobin more rapidly in first week as compared to second and third week in women with postpartum iron deficiency anemia. Hypersensitivity reaction, chest pain, dyspnoea reported with iron dextran and iron sorbitol citric acid were not observed with iron sucrose. Intravenous iron sucrose can be used safely to fill a rift between blood transfusion and oral iron in treatment of postpartum iron deficiency anemia

Efficacy, tolerability and safety of intravenous iron sucrose in postpartum anaemia

Background: Anemia is one of major contributing factor in maternal mortality and morbidity in third world countries and according to the WHO, contributes to 40% maternal deaths. Postpartum anemia is observed in up to 27% of women.It is a common problem throughout the world. Treatment of postpartum iron deficiency anemia includes oral and parenteral iron supplmentaion as well as blood transfusion in severe cases. Methods: This was a prospective longitudinal study carried out in Department of Obstetrics & Gynaecology of PRH, Loni. Total 80 women suffering from postpartum anemia of age above 18 years with haemoglobin (HB) level below 11gm/dl and above 6gm/dl were included for the study. After history taking, clinical examination and baseline Hb level, all of them were administered intravenous iron sucrose 200 mg per dose per day till the total calculated dose was administered. The post therapy evaluation was done with the estimation of Hb on day 1, day 7, day 14 and day 21. Results: 31.25% women belonged to the age group each of 19-21 years and 22-24 years. Maximum number of patients received 3 doses of IV Iron sucrose (i.e. total 600mg) followed by 2 doses (i.e. total 400mg), 4 doses (i.e. total 800mg) and 5 doses (i.e. total 1000mg) respectively. Hb level rises extremely significantly (p<0.001) after IV Iron Sucrose administration on day 1, 7, 14 & 21 as compared to corresponding values before delivery as analyzed by Friedman Test (Nonparametric Repeated Measures ANOVA) . 16 patients (20%) experienced thrombophlebitis to IV Iron Sucrose administration. About 12 (15%) patients experienced rigor followed by sweating in 10 patients (12.5%) and fever in 8 patients (10%). About 62 patients (77.5%) from total 80 reported well tolerability to IV Iron Sucrose while remaining 18 patients (22.5%) reported poor tolerability to IV Iron Sucrose Conclusion: Intravenous iron sucrose increases the haemoglobin more rapidly in first week as compared to second and third week in women with postpartum iron deficiency anemia. Hypersensitivity reaction, chest pain, dyspnoea reported with iron dextran and iron sorbitol citric acid were not observed with iron sucrose. Intravenous iron sucrose can be used safely to fill a rift between blood transfusion and oral iron in treatment of postpartum iron deficiency anemia

Assessing the capacity of a denoising diffusion probabilistic model to reproduce spatial context

Diffusion models have emerged as a popular family of deep generative models (DGMs). In the literature, it has been claimed that one class of diffusion models -- denoising diffusion probabilistic models (DDPMs) -- demonstrate superior image synthesis performance as compared to generative adversarial networks (GANs). To date, these claims have been evaluated using either ensemble-based methods designed for natural images, or conventional measures of image quality such as structural similarity. However, there remains an important need to understand the extent to which DDPMs can reliably learn medical imaging domain-relevant information, which is referred to as `spatial context' in this work. To address this, a systematic assessment of the ability of DDPMs to learn spatial context relevant to medical imaging applications is reported for the first time. A key aspect of the studies is the use of stochastic context models (SCMs) to produce training data. In this way, the ability of the DDPMs to reliably reproduce spatial context can be quantitatively assessed by use of post-hoc image analyses. Error-rates in DDPM-generated ensembles are reported, and compared to those corresponding to a modern GAN. The studies reveal new and important insights regarding the capacity of DDPMs to learn spatial context. Notably, the results demonstrate that DDPMs hold significant capacity for generating contextually correct images that are `interpolated' between training samples, which may benefit data-augmentation tasks in ways that GANs cannot.Comment: This paper is under consideration at IEEE TM

A Method for Evaluating the Capacity of Generative Adversarial Networks to Reproduce High-order Spatial Context

Generative adversarial networks are a kind of deep generative model with the potential to revolutionize biomedical imaging. This is because GANs have a learned capacity to draw whole-image variates from a lower-dimensional representation of an unknown, high-dimensional distribution that fully describes the input training images. The overarching problem with GANs in clinical applications is that there is not adequate or automatic means of assessing the diagnostic quality of images generated by GANs. In this work, we demonstrate several tests of the statistical accuracy of images output by two popular GAN architectures. We designed several stochastic object models (SOMs) of distinct features that can be recovered after generation by a trained GAN. Several of these features are high-order, algorithmic pixel-arrangement rules which are not readily expressed in covariance matrices. We designed and validated statistical classifiers to detect the known arrangement rules. We then tested the rates at which the different GANs correctly reproduced the rules under a variety of training scenarios and degrees of feature-class similarity. We found that ensembles of generated images can appear accurate visually, and correspond to low Frechet Inception Distance scores (FID), while not exhibiting the known spatial arrangements. Furthermore, GANs trained on a spectrum of distinct spatial orders did not respect the given prevalence of those orders in the training data. The main conclusion is that while low-order ensemble statistics are largely correct, there are numerous quantifiable errors per image that plausibly can affect subsequent use of the GAN-generated images.Comment: Submitted to IEEE-TPAMI. Early version with partial results has been accepted for poster presentation at SPIE-MI 202