Towards optimal multimode fiber imaging by leveraging input polarization and conditional generative adversarial networks

Deep learning techniques provide a plausible route towards achieving practical imaging through multimode fibers. However, the results produced by these methods are often influenced by physical factors like temperature, fiber length, external perturbations, and polarization state of the input light. The impact of other factors, except input light polarization, has been discussed in the literature for imaging applications. The input polarization has been considered by researchers while looking at the characterization and control of polarization in multimode fibers. Here, we show experimentally that the state of polarization of light, being injected at multimode fiber input, affects the fidelity of reconstructed images from speckle patterns. Certain polarization states produce high-quality images at fiber output, while some yield degraded results. We have designed a conditional generative adversarial network~(CGAN) for image regeneration at various degrees of input light polarization. We demonstrate that in the case of multimode fibers that are held fixed, optimal imaging can be achieved by leveraging our CGAN model with the input light polarization state, where the fidelity of images is maximum. Our work exhibits high average structural similarity index values exceeding 0.9, surpassing the previously reported value of 0.8772. We also show that the model can be generalized to image adequately for all input light polarization states when the fiber has bends or twists. We anticipate our work will be a stepping stone toward developing high-resolution and less invasive multimode fiber endoscopes

Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy

Optical resonant microcavities with ultra high quality factors are widely used for biosensing. Until now, the primary method of detection has been based upon tracking the resonant wavelength shift as a function of biodetection events. One of the sources of noise in all resonant-wavelength shift measurements is the noise due to intensity fluctuations of the laser source. An alternative approach is to track the change in the quality factor of the optical cavity by using phase shift cavity ring down spectroscopy, a technique which is insensitive to the intensity fluctuations of the laser source. Here, using biotinylated microtoroid resonant cavities, we show simultaneous measurement of the quality factor and the wavelength shift by using phase shift cavity ring down spectroscopy. These measurements were performed for disassociation phase of biotin-streptavidin reaction. We found that the disassociation curves are in good agreement with the previously published results. Hence, we demonstrate not only the application of phase shift cavity ring down spectroscopy to microcavities in the liquid phase but also simultaneous measurement of the quality factor and the wavelength shift for the microcavity biosensors in the application of kinetics measurements

Learning from the past: Analysis of disaster management structures, policies and institutions in Pakistan

Purpose: The paper provides a historical analysis of the disaster management structure, policies and institutions in Pakistan between 1947 and 2005, and highlights the contemporary challenges in view of the learning from the past. Design/methodology/approach: The paper uses a historic-integrative case study approach to disaster management and risk reduction policy, planning and practice. Qualitative data was collected through purposive sampling and a case study design was adopted. A broad range of actors was recruited as research participants. In total, 22 semi-structured in-depth interviews were conducted in relation to this study in six different districts of Pakistan to achieve insight into the role of different institutions and stakeholders. Findings: Overall, the post-colonial flood-centric policy framework and fragmented responsibilities of different disaster management institutions show the lack of an effective institutional structure for disaster management and mitigation in Pakistan, particularly at the local level. Until the event of the 2005 earthquake, policies heavily relied on attaining immediate and short-term goals of Response and Relief while ignoring the long-term objectives of strategic planning for Prevention and Preparedness as well as capacity building and empowerment of local institutions and communities. Practical implications: The analysis explains, in part, why disaster planning and management needs to be given due attention in the developing countries at different policy scales (from local to national) especially in the face of limited resources, and what measures should be taken to improve effectiveness at different phases of the disaster management cycle. Originality/value: The paper advances the importance of a historical case study approach to disaster management and mitigation. The empirical work provides original research evidence about the approaches to dealing with disasters in Pakistan and thus enriches existing knowledge of disaster management policy and planning about the country

Accurate determination of the quality factor and tunneling distance of axisymmetric resonators for biosensing applications

Due to ultra high quality factor ($10^6-10^9$), axisymmetric optical microcavities are popular platforms for biosensing applications. It has been recently demonstrated that a microcavity biosensor can track a biodetection event as a function of its quality factor by using phase shift cavity ring down spectroscopy (PS-CRDS). However, to achieve maximum sensitivity, it is necessary to optimize the microcavity parameters for a given sensing application. Here, we introduce an improved finite element model which allows us to determine the optimized geometry for the PS-CRDS sensor. The improved model not only provides fast and accurate determination of quality factors but also determines the tunneling distance of axisymmetric resonators. The improved model is validated numerically, analytically, and experimentally.Comment: Published in Optics Express, April 2, 201

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Microcontroller-based Sonar Ultrasonic Water Level Control System with Closed-loop Control Approach

This study proposes a microcontroller-based closed-loop water level control system that utilizes a sonar ultrasonic sensor to monitor and regulate water levels in a tank. The system operates by continuously checking the water level in the tank and adjusting the valve’s opening and closure times to maintain the desired water level. The closed-loop control approach employed by the system offers a precise water level control solution that can significantly reduce water waste in water pumping systems. The paper also assesses the theoretical and experimental response of an open-loop water level control system. The findings demonstrate that the closed-loop system outperforms the open-loop system, indicating the effectiveness of the proposed approach in maintaining water levels in a tank. The proposed system is not only applicable to water pumping systems but can also be used to manage the flow of hot and cold water from home water heaters. Additionally, the system can be utilized in various industries that require level or flow control, with particular emphasis on the production of distilled water, juice, and milk

Treatment of blood blister aneurysms of the internal carotid artery with flow diversion.

BACKGROUND: Blood blister aneurysms (BBA) are a rare subset of intracranial aneurysms that represent a therapeutic challenge from both a surgical and endovascular perspective. OBJECTIVE: To report multicenter experience with flow diversion exclusively for BBA, located at non-branching segments along the anteromedial wall of the supraclinoidal internal carotid artery (ICA). METHODS: Consecutive cases of BBA located at non-branching segments along the anteromedial wall of the supraclinoidal ICA treated with flow diversion were included in the final analysis. RESULTS: 49 patients with 51 BBA of the ICA treated with devices to achieve the flow diversion effect were identified. 43 patients with 45 BBA of the ICA were treated with the pipeline embolization device and were included in the final analysis. Angiographic follow-up data were available for 30 patients (32 aneurysms in total); 87.5% of aneurysms (28/32) showed complete obliteration, 9.4% (3/32) showed reduced filling, and 3.1% (1/32) persistent filling. There was no difference between the size of aneurysm (≤2 mm vs \u3e2 mm) or the use of adjunct coiling and complete occlusion of the aneurysm on follow-up (P=0.354 and P=0.865, respectively). Clinical follow-up data were available for 38 of 43 patients. 68% of patients (26/38) had a good clinical outcome (modified Rankin scale score of 0-2) at 3 months. There were 7 (16%) immediate procedural and 2 (5%) delayed complications, with 1 case of fatal delayed re-rupture after the initial treatment. CONCLUSIONS: Our data support the use of a flow diversion technique as a safe and effective therapeutic modality for BBA of the supraclinoid ICA