Foundry technology and services for si photonics

We discuss the progress in development and offering of silicon photonic integration platforms based on 200mm and 300mm wafer technologies. Devices have capability for developing high-speed datacommunication, but are also used for life science applications

CMOS Integrated Optics - Studies on Submicron Waveguide Mode Properties and Devices

The aim of this thesis is to demonstrate novel or improved photonic devices based on the CMOS based photonics processes. Methods to obtain application-specific optical mode characteristics through design, fabrication and post-processing are proposed. Focus is on devices attainable within the capabilities of 130 nm CMOS node tool-set, thereby ensuring manufacturability of photonic devices studied in this thesis. Compared to the widely studied 1D polarization sensitive slot waveguides, we demonstrate novel designs for 2D slot waveguides with high confinement for both polarizations of the fundamental optical mode (quasi-TE and quasi-TM). It is shown that on the basis of required optical mode characteristics such as effective index, birefringence, confinement and mode overlap; cross-slot waveguide, closed 2D slot waveguide, open 2D slot waveguide or u-slot waveguide can be used. It is also shown that angled sidewall in vertical slot waveguide aides void-less filling of the narrow vertical slot waveguide and enhances interaction with the non-linear slot. Asymmetric vertical slot waveguides to achieve non-reciprocal phase shift are also discussed. Furthermore, unprecedented reduction of optical propagation loss is demonstrated for the shorter wavelength regime (980 nm) in the CMOS based silicon nitride material system. This is realized through CMOS compatible ALD based wafer-scale post-processing technique

Characterization of silicon micro-optical waveguides

In modern electronic circuitry, electrical interconnects have not kept pace with increasing electronic processing speed. Various drawbacks of electrical domain viz. bandwidth limitation, signal delay, electromagnetic wave phenomenon propelled the use of optical fibers. Optical waveguides provide a novel solution because of the absence of these phenomena in the optical domain. Various materials like polymers, III-V semiconductor compounds, LiNbO3 etc. have been analyzed for fabricating optical waveguides. We have chosen silicon as a material for optical waveguides. Silicon is extensively used for complimentary metal oxide semiconductor (CMOS) transistor fabrication. Thus, to use silicon for fabricating optical components is highly favorable from a technological standpoint. In this thesis, we characterize silicon optical waveguides. Loss in 10µm wide hydrogenated amorphous silicon (a-Si:H) strip optical waveguides is estimated to be 1.5dB/cm and 0.1dB/cm in rib type silicon on insulator (SOI) optical waveguides. Reflectivity of Bragg mirror on a-Si:H strip waveguides is in the range 49-86%. We measured 0.5-1dB loss per etched mirror section for fundamental transverse electric (TE) and transverse magnetic (TM) modes propagating in SOI rib waveguide. A setup to measure birefringence in optical waveguides is discussed and its results are analyzed. Ellipsometry of 260nm thick layer of a-Si:H, deposited by plasma enhanced chemical vapor deposition (PECVD), is done to ascertain the material refractive index. Spectral behavior of a-Si:H waveguides using a supercontinuum source is also studied

Multi-processor Scheduling to Minimize Flow Time with epsilon Resource Augmentation

We investigate the problem of online scheduling of jobs to minimize flow time and stretch on m identical machines. We consider the case where the algorithm is given either (1 + ε)m machines or m machines of speed (1 + ε), for arbitrarily small ε \u3e 0. We show that simple randomized and deterministic load balancing algorithms, coupled with simple single machine scheduling strategies such as SRPT (shortest remaining processing time) and SJF (shortest job first), are O(poly(1/ε))-competitive for both flow time and stretch. These are the first results which prove constant factor competitive ratios for flow time or stretch with arbitrarily small resource augmentation. Both the randomized and the deterministic load balancing algorithms are non- migratory and do immediate dispatch of jobs. The randomized algorithm just allocates each incoming job to a random machine. Hence this algorithm is non- clairvoyant, and coupled with SETF (shortest elapsed time first), yields the first non-clairvoyant algorithm which is con- stant competitive for minimizing flow time with arbitrarily small resource augmentation. The deterministic algorithm that we analyze is due to Avrahami and Azar. For this algorithm, we show O(1/ε)-competitiveness for total flow time and stretch, and also for their Lp norms, for any fixed p ≥ 1

Estimation of vitamin D level in low backache cases and their outcome after treatment with vitamin D

Background: Vitamin D has a significant role to play in bone metabolism and neuromuscular function. Several researchers have indicated that vitamin D deficiency may be possibly related to chronic musculoskeletal pain including chronic low back pain (CLBP). Objectives of this present study were conducted to rule out the vitamin D deficiency in a patient can also be a cause of low backache other than various spinal disorders like PIVD, spondylolisthesis etc.  Methods: A total of 50 patients, of any age who visited the Department of Orthopedics outpatient/Emergency, with chief complaint of low backache without any low backache disease like PIVD and spondylolisthesis etc. were thoroughly interviewed and examined for any concomitant pathological disease of spine. Patient’s Blood sample of about 5 ml with syringe of 10 cc. were taken and the serum vitamin D level was assayed by “direct competitive chemiluminescence immunoassay” (CLIA). Results: Out of 50 patients of low backache and vitamin D deficiency, 33 patients have good outcome in their pain after getting treatment in form of Vitamin D.  Conclusions: We concluded that the vitamin D plays a major role in low backache and after treatment there is significant improvement in low backache.  

SAFETY OF HYDROXYCHLOROQUINE FOR COVID-19 PROPHYLAXIS AMONG HEALTHCARE WORKERS: AN OBSERVATIONAL STUDY

Objective: Indian Council of Medical Research recommended hydroxychloroquine (HCQ) for prophylaxis of COVID‐19 for healthcare workers and the Food and Drug Administration approved its use in the treatment and prophylaxis of COVID‐19 disease. Even though HCQ is adequately tolerated in usual circumstances, still questions about the harmful effects of the drug remain a cause for concern in adults treated with HCQ. The objective of this study was to evaluate the major and minor adverse effects of prophylactic HCQ for COVID-19 among healthcare workers. Methods: Our analysis was intended to analyze HCQ’s adverse drug reaction profile for COVID‐19 prophylaxis in prophylactic doses in health-care staff. This was a cross-sectional study carried out among healthcare workers taking HCQ prophylaxis for COVID‑19. The study was carried out over 08 weeks period from April to May 2020. The data were obtained regarding age, sex, comorbidities, and possible adverse effects. A pretested and validated online questionnaire was provided to the participants to assess the harmful effects that they experienced when taking HCQ. Furthermore, pre and post 8 weeks prophylaxis, individuals underwent general and systemic examination, along with ECG and blood sugar level monitoring. Results: The research group comprised 70 previously healthy and health-care staff. In 70 patients, 27 minor adverse effects were reported (18.9%). Headache was the most frequently reported symptoms followed by nausea and vomiting, itching, and skin rashes. There was no statistically relevant variation in harmful effects due to age or number of doses administered. However, none of the adverse effects was serious or debilitating. Conclusion: With adequate pre-prophylaxis evaluation, health education, and regular monitoring, HCQ prophylaxis is safe and devoid of any serious adverse effects in previously healthy individuals

Post-transcriptional regulation of IGF1R by key microRNAs in long-lived mutant mice

Long-lived mutant mice, both Ames dwarf and growth hormone receptor genedisrupted or knockout strains, exhibit heightened cognitive robustness and altered IGF1 signaling in the brain. Here, we report, in both these long-lived mice, that three up-regulated lead microRNAs, miR-470, miR-669b, and miR-681, are involved in posttranscriptional regulation of genes pertinent to growth hormone/IGF1 signaling. All three are most prominently localized in the hippocampus and correspond to reduced expression of key IGF1 signaling genes: IGF1, IGF1R, and PI3 kinase. The decline in these genes expression translates into decreased phosphorylation of downstream molecules AKT and FoxO3a. Cultures transfected with either miR-470, miR-669b, or miR-681 show repressed endogenous expression of all three genes of the IGF1 signaling axis, most significantly IGF1R, while other similarly up-regulated microRNAs, including let-7g and miR-509, do not induce the same levels of repression. Transduction study in IGF1-responsive cell cultures shows significantly reduced IGF1R expression, and AKT to some extent, most notably by miR-681. This is accompanied by decreased levels of downstream phosphorylated forms of AKT and FoxO3a upon IGF1 stimulation. Suppression of IGF1R by the three microRNAs is further validated by IGF1R 3\u27UTR reporter assays. Taken together, our results suggest that miR-470, miR-669b, and miR-681 are all functionally able to suppress IGF1R and AKT, two upstream genes controlling FoxO3a phosphorylation status. Their up-regulation in growth hormone signaling-deficient mutant mouse brain suggests reduced IGF1 signaling at the posttranscriptional level, for numerous gains of neuronal function in these long-lived mice

The snoRNA MBII-52 (SNORD 115) is processed into smaller RNAs and regulates alternative splicing

The loss of HBII-52 and related C/D box small nucleolar RNA (snoRNA) expression units have been implicated as a cause for the Prader-Willi syndrome (PWS). We recently found that the C/D box snoRNA HBII-52 changes the alternative splicing of the serotonin receptor 2C pre-mRNA, which is different from the traditional C/D box snoRNA function in non-mRNA methylation. Using bioinformatic predictions and experimental verification, we identified five pre-mRNAs (DPM2, TAF1, RALGPS1, PBRM1 and CRHR1) containing alternative exons that are regulated by MBII-52, the mouse homolog of HBII-52. Analysis of a single member of the MBII-52 cluster of snoRNAs by RNase protection and northern blot analysis shows that the MBII-52 expressing unit generates shorter RNAs that originate from the full-length MBII-52 snoRNA through additional processing steps. These novel RNAs associate with hnRNPs and not with proteins associated with canonical C/D box snoRNAs. Our data indicate that not a traditional C/D box snoRNA MBII-52, but a processed version lacking the snoRNA stem is the predominant MBII-52 RNA missing in PWS. This processed snoRNA functions in alternative splice-site selection. Its substitution could be a therapeutic principle for PW

Inhibition of preS1-hepatocyte interaction by an array of recombinant human antibodies from naturally recovered individuals

Neutralizing monoclonal antibodies are being found to be increasingly useful in viral infections. In hepatitis B infection, antibodies are proven to be useful for passive prophylaxis. The preS1 region (21–47a.a.) of HBV contains the viral hepatocyte-binding domain crucial for its attachment and infection of hepatocytes. Antibodies against this region are neutralizing and are best suited for immune-based neutralization of HBV, especially in view of their not recognizing decoy particles. Anti-preS1 (21–47a.a.) antibodies are present in serum of spontaneously recovered individuals. We generated a phage-displayed scFv library using circulating lymphocytes from these individuals and selected four preS1-peptide specific scFvs with markedly distinct sequences from this library. All the antibodies recognized the blood-derived and recombinant preS1 containing antigens. Each scFv showed a discrete binding signature, interacting with different amino acids within the preS1-peptide region. Ability to prevent binding of the preS1 protein (N-terminus 60a.a.) to HepG2 cells stably expressing hNTCP (HepG2-hNTCP-C4 cells), the HBV receptor on human hepatocytes was taken as a surrogate marker for neutralizing capacity. These antibodies inhibited preS1-hepatocyte interaction individually and even better in combination. Such a combination of potentially neutralizing recombinant antibodies with defined specificities could be used for preventing/managing HBV infections, including those by possible escape mutants