Investigation of Different Transfer Functions for Optical Limiting Amplifier used in a 2R Burst Mode Optical Regenerator

The major difference between a continuous mode optical regenerator (CMOR) and a burst mode optical regenerator (BMOR) is that a BMOR is capable of handling large variations in the input power which makes it useful in optical packet switched and optical burst switched networks. This is due to the optical limiting amplifier (OLA) present in the BMOR. Using computer modelling, the impact of using different OLA non-linear transfer functions on the output bit error rate of a system consisting of a cascade of 2R BMORs has been investigated.  The effect of amplified spontaneous emission (ASE) noise introduced in the inter-regenerator links has also been taken into consideration.

Probabilistic Hierarchical Forecasting with Deep Poisson Mixtures

Hierarchical forecasting problems arise when time series have a natural group structure, and predictions at multiple levels of aggregation and disaggregation across the groups are needed. In such problems, it is often desired to satisfy the aggregation constraints in a given hierarchy, referred to as hierarchical coherence in the literature. Maintaining hierarchical coherence while producing accurate forecasts can be a challenging problem, especially in the case of probabilistic forecasting. We present a novel method capable of accurate and coherent probabilistic forecasts for hierarchical time series. We call it Deep Poisson Mixture Network (DPMN). It relies on the combination of neural networks and a statistical model for the joint distribution of the hierarchical multivariate time series structure. By construction, the model guarantees hierarchical coherence and provides simple rules for aggregation and disaggregation of the predictive distributions. We perform an extensive empirical evaluation comparing the DPMN to other state-of-the-art methods which produce hierarchically coherent probabilistic forecasts on multiple public datasets. Compared to existing coherent probabilistic models, we obtained a relative improvement in the overall Continuous Ranked Probability Score (CRPS) of 11.8% on Australian domestic tourism data, and 8.1% on the Favorita grocery sales dataset.Comment: Probabilistic Hierarchical Forecasting, Neural Networks, Poisson Mixtures, Preprint submitted to IJ

Prevalence and pattern of congenital heart diseases in Karimnagar, Andhra Pradesh, India: diagnosed clinically and by trans-thoracic-two-dimensional echocardiography

Background: To find the prevalence and pattern of congenital heart diseases (CHD) at a Semi-Urban teaching hospital in Karimnagar, Andhra Pradesh, India.Methods: A thorough history, clinical examination and Trans-Thoracic-Two-Dimensional Echocardiography (TTE) was done for all the live birth, children up to 18years of age and patients between 18 to 25 years, who were referred or presented to the Department of Medicine, Chalmeda Anand Rao Institute of Medical Sciences, Bommakal, Karimnagar (AP), over a period of 5 years from July 2008 through June 2013. Those suspected to having a CHD or referred in our department, were further evaluated with: Clinically, Twelve-Lead-Surface Electrocardiography, Chest Radiography and the diagnosis was confirmed by TTE. Trans-Thoracic-Two-Dimensional Echocardiography, M-Mode, Color flow doppler and Spectral doppler echocardiography was done in all patients in the various views.Results: Total 13,554 patients were examined and underwent TTE. Out of 13,554 patients 116 were identified as having congenital heart diseases, thus giving a prevalence of 8.55 per 1,000 live births. Isolated Ventricular septal defect (28.44%), isolated atrial septal defect (18.10%), Patent ductus arteriosus (10.34%), isolated congenital pulmonary stenosis (6.03%) and tetralogy of Fallot’s (6.03%), were the commonest defects observed and confirmed by TTE. TOF was the main cyanotic CHD (6.03%), with the prevalence of 0.51% per 1,000 live births. VSD, ASD and PDA were more prevalent in males. TOF and Complete A.V. Canal defect was prevalent in females. All small size muscular and perimembranous VSD was closed spontaneously. Spontaneous closure rate of 75.00% in Muscular VSD and 52.17% in perimembranous VSD was observed. Spontaneous closure rate of Ostium secundum type ASD was 53.33%. Conclusions: The prevalence of CHD at a tertiary teaching hospital (CAIMS, Bommakal, Karimnagar, AP, India), is 8.55 per 1,000 live births. VSD, ASD, PDA are the most common acyanotic and TOF was the commonest cyanotic congenital heart defects respectively. Non-Invasive Cardiac diagnostic technique (like TTE) plays major in the diagnosis of CHD. When clinical evidences lead to suspicion of congenital heart defect, an echocardiography should be performed immediately.

Mapping dusty galaxy growth at z>5z>5 with FRESCO: Detection of Hα\alpha in submm galaxy HDF850.1 and the surrounding overdense structures

We report the detection of a 13$\sigma$ H$\alpha$ emission line from HDF850.1 at $z=5.188\pm0.001$ using the FRESCO NIRCam F444W grism observations. Detection of H$\alpha$ in HDF850.1 is noteworthy, given its high far-IR luminosity, substantial dust obscuration, and the historical challenges in deriving its redshift. HDF850.1 shows a clear detection in the F444W imaging data, distributed between a northern and southern component, mirroring that seen in [CII] from the Plateau de Bure Interferometer. Modeling the SED of each component separately, we find that the northern component has a higher mass, star formation rate (SFR), and dust extinction than the southern component. The observed H$\alpha$ emission appears to arise entirely from the less-obscured southern component and shows a similar $\Delta$v$\sim$+130 km/s velocity offset to that seen for [CII] relative to the source systemic redshift. Leveraging H$\alpha$-derived redshifts from FRESCO observations, we find that HDF850.1 is forming in one of the richest environments identified to date at $z>5$, with 100 $z=5.17-5.20$ galaxies distributed across 10 structures and a $\sim$(15 cMpc)$^3$ volume. Based on the evolution of analogous structures in cosmological simulations, the $z=5.17-5.20$ structures seem likely to collapse into a single $>$10$^{14}$ $M_{\odot}$ cluster by $z\sim0$. Comparing galaxy properties forming within this overdensity with those outside, we find the masses, SFRs, and $UV$ luminosities inside the overdensity to be clearly higher. The prominence of H$\alpha$ line emission from HDF850.1 and other known highly-obscured $z>5$ galaxies illustrates the potential of NIRCam-grism programs to map both the early build-up of IR-luminous galaxies and overdense structures.Comment: Submitted to MNRAS. 20 pages, 10 figures and 8 tables (including appendices

Types of the cerebral arterial circle (circle of Willis) in a Sri Lankan Population

<p>Abstract</p> <p>Background</p> <p>The variations of the circle of Willis (CW) are clinically important as patients with effective collateral circulations have a lower risk of transient ischemic attack and stroke than those with ineffective collaterals. The aim of the present cadaveric study was to investigate the anatomical variations of the CW and to compare the frequency of prevalence of the different variations with previous autopsy studies as variations in the anatomy of the CW as a whole have not been studied in the Indian subcontinent.</p> <p>Methods</p> <p>The external diameter of all the arteries forming the CW in 225 normal Sri Lankan adult cadaver brains was measured using a calibrated grid to determine the prevalence in the variation in CW. Chisquared tests and a correspondence analysis were performed to compare the relative frequencies of prevalence of anatomical variations in the CW across 6 studies of diverse ethnic populations.</p> <p>Results</p> <p>We report 15 types of variations of CW out of 22 types previously described and one additional type: hypoplastic precommunicating part of the anterior cerebral arteries (A1) and contralateral posterior communicating arteries (PcoA) 5(2%). Statistically significant differences (p < 0.0001) were found between most of the studies except for the Moroccan study. An especially notable difference was observed in the following 4 configurations: 1) hypoplastic precommunicating part of the posterior cerebral arteries (P1), and contralateral A1, 2) hypoplastic PcoA and contralateral P1, 3) hypoplastic PcoA, anterior communicating artery (AcoA) and contralateral P1, 4) bilateral hypoplastic P1s and AcoA in a Caucasian dominant study by Fisher versus the rest of the studies.</p> <p>Conclusion</p> <p>The present study reveals that there are significant variations in the CW among intra and inter ethnic groups (Caucasian, African and Asian: Iran and Sri Lanka dominant populations), and warrants further studies keeping the methods of measurements, data assessment, and the definitions of hypoplasia the same.</p

PyPose: A Library for Robot Learning with Physics-based Optimization

Deep learning has had remarkable success in robotic perception, but its data-centric nature suffers when it comes to generalizing to ever-changing environments. By contrast, physics-based optimization generalizes better, but it does not perform as well in complicated tasks due to the lack of high-level semantic information and the reliance on manual parametric tuning. To take advantage of these two complementary worlds, we present PyPose: a robotics-oriented, PyTorch-based library that combines deep perceptual models with physics-based optimization techniques. Our design goal for PyPose is to make it user-friendly, efficient, and interpretable with a tidy and well-organized architecture. Using an imperative style interface, it can be easily integrated into real-world robotic applications. Besides, it supports parallel computing of any order gradients of Lie groups and Lie algebras and $2^{\text{nd}}$-order optimizers, such as trust region methods. Experiments show that PyPose achieves 3-20$\times$ speedup in computation compared to state-of-the-art libraries. To boost future research, we provide concrete examples across several fields of robotics, including SLAM, inertial navigation, planning, and control