R2R^2 inflation to probe non-perturbative quantum gravity

It is natural to expect a consistent inflationary model of the very early Universe to be an effective theory of quantum gravity, at least at energies much less than the Planck one. For the moment, $R+R^2$, or shortly $R^2$, inflation is the most successful in accounting for the latest CMB data from the PLANCK satellite and other experiments. Moreover, recently it was shown to be ultra-violet (UV) complete via an embedding into an analytic infinite derivative (AID) non-local gravity. In this paper, we derive a most general theory of gravity that contributes to perturbed linear equations of motion around maximally symmetric space-times. We show that such a theory is quadratic in the Ricci scalar and the Weyl tensor with AID operators along with the Einstein-Hilbert term and possibly a cosmological constant. We explicitly demonstrate that introduction of the Ricci tensor squared term is redundant. Working in this quadratic AID gravity framework without a cosmological term we prove that for a specified class of space homogeneous space-times, a space of solutions to the equations of motion is identical to the space of backgrounds in a local $R^2$ model. We further compute the full second order perturbed action around any background belonging to that class. We proceed by extracting the key inflationary parameters of our model such as a spectral index ($n_s$), a tensor-to-scalar ratio ($r$) and a tensor tilt ($n_t$). It appears that $n_s$ remains the same as in the local $R^2$ inflation in the leading slow-roll approximation, while $r$ and $n_t$ get modified due to modification of the tensor power spectrum. This class of models allows for any value of $r<0.07$ with a modified consistency relation which can be fixed by future observations of primordial $B$-modes of the CMB polarization. This makes the UV complete $R^2$ gravity a natural target for future CMB probes.Comment: 37 page

Comparative Study of PID Based VMC and Fuzzy Logic Controllers for Flyback Converter

In this paper performance of flyback converter by using PID controller and Fuzzy controller are studied, compared and analyzed. The above study is done for 200W, 230V A.C input 48V DC output. Design of fuzzy controller is based on the heuristic knowledge of converter behaviour, and tuning of fuzzy inference requires some expertise to minimize unproductive trial and error. The design of PID control is based on the frequency response of the converter. For the DC-DC converters, the performance of the fuzzy controller was superior in some respects to that of the PID controller. The fuzzy controller is easily to develop, they cover a wide range of operating conditions, and they are more readily customizable in natural language terms. Simulation is done in Matlab environment to show the performance variations of above mentioned converters using both Fuzzy & PID controllers

Cosmology in nonlocal gravity

In this chapter we review the recent developments of realizing $R^2$-like inflation in the framework of a most general UV nonlocal extension of Einstein's general theory of relativity (GR). It is a well-motivated robust approach towards quantum gravity. In the past decades, nonlocal gravitational theories which are quadratic in curvature have been understood to be ghost-free and super-renormalizable around maximally symmetric spacetimes. However, in the context of early Universe cosmology we show that one must go beyond the quadratic curvature nonlocal gravity in order to achieve a consistent ghost-free framework of Universe evolution from quasi de Sitter to Minkowski spacetime. In this regard, we discuss a construction of a most general nonlocal gravity action that leads to $R^2$-like inflation and discuss the corresponding observational predictions for the scalar and tensor spectral tilts, tensor-to-scalar ratio, and the primordial non-Gaussianities. We present an analysis of how the nonlocal inflationary cosmology goes beyond the established notions of effective field theories of inflation. Finally, we comment on some open questions and prospects of higher curvature nonlocal gravity on its way of achieving the UV completion.Comment: 31 pages, 4 figures, Invited chapter of the Handbook of Quantum Gravity, C. Bambi, L. Modesto and I.L. Shapiro (Eds.), Springer, expected in 202

Early Enteral Feeding Vs Late Enteral Feeding in patients undergoing Upper gastrointestinal surgery in Government Rajaji Hospital, Madurai

INTRODUCTION: Post operative ‘nil per mouth’ is the most commonly practiced methodology after a patient undergoes upper gastrointestinal surgeries like gastrectomy, gatrojejunal anastamosis and closure of perforated stomach or duodenum. The rationale behind that was to give time for the anastamosis to heal before being challenged by liquid or solid diets and to prevent post operative nausea and vomiting. The concept of early enteral feeding though having proper advantages has not had widespread following. Contrary to the commonly known opinion the oral feeds following upper gastrointestinal surgeries would increase the risk of anastamotic dehiscence and also worsen the ileus of the bowel, early feeds are absorbed well and also have a faster recovery of paralytic ileus, cause lesser septic complications, improve nutrition and lesser hospital stay. OBJECTIVE: To show the advantages of starting the patients undergoing upper gastrointestinal surgeries on early feeding using a nasojejunal tube with milk based diet over the conventional late enteral feeding. METHODOLOGY: Two groups of patients with 25 in each are put up as study and control groups. Patients in the study group are inserted a nasojejunal tube during surgery and started on early enteral feeding with milk based diet following the feeding protocol. Control groups are managed by conventional nil per mouth and late enteral feeding. The parameters monitored are patient weight, haemoglobin, S.albumin, duration of paralytic ileus, time taken to start oral feeds, duration of hospital stay, septic complications and surgical site infections. RESULTS: The mean age of the patients in the study group was 46.88yrs whereas in the control group was 47.96yrs. The mean weight of the study cases pre operatively was 57.56 kg but weight increased to about 58.6kg by post operative day 7.The same was not seen in control cases. . The mean pre operative haemoglobin among the cases in study group was 9.7g% and levels increased to 9.98g% by post operative day7. The same was not seen in control group. The pre operative S.albumin levels among the patients started on early feeding was 2.74g/dl and by post operative day7 it was 3.13g%. The same increase was not observed in control patients. The mean duration of paralytic ileus among the cases in the study group was 2.4 days whereas in the control group was 4.04 days. The mean duration taken to start oral feeds is 4.4 days in study group when compared to those cases in the control group where the mean duration is 6 days. The rate of anastamotic leak when comparing both groups was not significant. Among the control group patients in the study about 9 patients developed surgical site infection when compared to to nil patients in study group. Septic complications like pneumonia and urinary tract infections developed in 2 cases of the study group whereas 13 cases in the control group developed the same. Side effects due to feeds were seen among 13 patients of the study group. The mean duration of hospital stay among the patients of the study group was 7.6 days whereas among those in the control group was 10.2 days. CONCLUSION: This study clearly proves that early enteral feeding has great advantages over the conventional method of late enteral feeding in patients undergoing upper gastrointestinal surgeries and that it can be followed as a routine for better post operative outcomes

Non-Gaussianities and tensor-to-scalar ratio in non-local R ²-like inflation

In this paper we will study $R^2$-like inflation in a non-local modification of gravity which contains quadratic in Ricci scalar and Weyl tensor terms with analytic infinite derivative form-factors in the action. It is known that the inflationary solution of the local $R+R^2$ gravity remains a particular exact solution in this model. It was shown earlier that the power spectrum of scalar perturbations generated during inflation in the non-local setup remains the same as in the local $R+R^2$ inflation, whereas the power spectrum of tensor perturbations gets modified due to the non-local Weyl tensor squared term. In the present paper we go beyond 2-point correlators and compute the non-Gaussian parameter $f_{NL}$ related to 3-point correlations generated during inflation, which we found to be different from those in the original local inflationary model and scenarios alike based on a local gravity. We evaluate non-local corrections to the scalar bi-spectrum which give non-zero contributions to squeezed, equilateral and orthogonal configurations. We show that $f_{NL}\sim O(1)$ with an arbitrary sign is achievable in this model based on the choice of form-factors and the scale of non-locality. We present the predictions for the tensor-to-scalar ratio, $r$, and the tensor tilt, $n_t$. In contrast to standard inflation in a local gravity, here the possibility $n_t$>0 is not excluded. Thus, future CMB data can probe non-local behaviour of gravity at high space-time curvatures.Comment: 40 pages, 6 figures; v2 matching the one published in JHEP, further discussion on the single field consistency relation is adde

Quasi Switched Capacitor based integrated Boost Series Parallel Fly-back Converter for energy Storage Applications

711-715A quasi-Switched Capacitor technique (QSC) is used to control the switch in Interconnected Boost Series Parallel Fly-Back Converter (IBSPFC). The QSC based IBSPFC does not require any snubber circuits for all the MOSFET switches presented at primary and secondary side and power can also be transferred even if one the winding gets damage. The primary side winding of the fly-back transformer is coupled in series across with bulk capacitor to minimize switch voltage stress and the secondary winding of the 1:1 fly-back transformer is coupled with dc voltage source, three switches and capacitor which forms a Quasi switched capacitor technique. Working techniques of quasi-switched capacitor with IBSPFC have been introduced. A 75v input, 100v output and DC-DC isolated Converter switching at frequency of 100 kHz is modeled using FPGA SPARTAN6LX9 and experimental results have been presented