SPECTROSCOPIC STUDIES OF Er3+DOPED IN SOL-GEL SILICA GLASS

Trivalent Erbium ions (Er3+) doped in silica glass was prepared by sol-gel technique which relies on the chemical reaction of liquid precursors to form the glass. Absorption spectrum was recorded in the visible region which shows several peaks resulting from the transition from ground state 4I15/2 to various excited states. The optical absorption has been investigated using Judd-Ofelt (J-O) theory. J-O parameters were obtained from the absorption spectrum. Large value of the parameter Ω2 shows that the bonding of the dopant to the host network is more covalent than ionic

Spectroscopic properties of Sm3+ and CdS co-doped in sol-gel silica glass

Sm3+- doped silica glass co-doped with CdS nanoparticles have been prepared by sol-gel method. FTIR spectra of the samples at different annealing temperatures show the gradual removal of hydroxyl group. XRD pattern shows crystalline nature of the silica host along with CdS peak. The optical absorption and fluorescence properties have been investigated using Judd-Ofelt theory. The Judd-Ofelt intensity parameters have been obtained from the absorption spectrum following the trend Ω2 > Ω4 > Ω6 and the large value of Ω2 indicates covalency of the rare earth bonding. Under excitation with 370 nm, photoluminescence peaks have been observed in the green, yellow, orange and red region as a result of radiative relaxation from the 4G5/2 state

Spectroscopic properties of Sm3+ and CdS co-doped in sol-gel silica glass

157-163Sm3+- doped silica glass co-doped with CdS nanoparticles have been prepared by sol-gel method. FTIR spectra of the samples at different annealing temperatures show the gradual removal of hydroxyl group. XRD pattern shows crystalline nature of the silica host along with CdS peak. The optical absorption and fluorescence properties have been investigated using Judd-Ofelt theory. The Judd-Ofelt intensity parameters have been obtained from the absorption spectrum following the trend Ω2 > Ω4 > Ω6 and the large value of Ω2 indicates covalency of the rare earth bonding. Under excitation with 370 nm, photoluminescence peaks have been observed in the green, yellow, orange and red region as a result of radiative relaxation from the 4G5/2 state

MaPLe: Multi-modal Prompt Learning

Pre-trained vision-language (V-L) models such as CLIP have shown excellent generalization ability to downstream tasks. However, they are sensitive to the choice of input text prompts and require careful selection of prompt templates to perform well. Inspired by the Natural Language Processing (NLP) literature, recent CLIP adaptation approaches learn prompts as the textual inputs to fine-tune CLIP for downstream tasks. We note that using prompting to adapt representations in a single branch of CLIP (language or vision) is sub-optimal since it does not allow the flexibility to dynamically adjust both representation spaces on a downstream task. In this work, we propose Multi-modal Prompt Learning (MaPLe) for both vision and language branches to improve alignment between the vision and language representations. Our design promotes strong coupling between the vision-language prompts to ensure mutual synergy and discourages learning independent uni-modal solutions. Further, we learn separate prompts across different early stages to progressively model the stage-wise feature relationships to allow rich context learning. We evaluate the effectiveness of our approach on three representative tasks of generalization to novel classes, new target datasets and unseen domain shifts. Compared with the state-of-the-art method Co-CoOp, MaPLe exhibits favorable performance and achieves an absolute gain of 3.45% on novel classes and 2.72% on overall harmonic-mean, averaged over 11 diverse image recognition datasets. Our code and pre-trained models are available at https://github.com/muzairkhattak/multimodal-prompt-learning.Comment: Accepted at CVPR202

Fine-tuned CLIP Models are Efficient Video Learners

Large-scale multi-modal training with image-text pairs imparts strong generalization to CLIP model. Since training on a similar scale for videos is infeasible, recent approaches focus on the effective transfer of image-based CLIP to the video domain. In this pursuit, new parametric modules are added to learn temporal information and inter-frame relationships which require meticulous design efforts. Furthermore, when the resulting models are learned on videos, they tend to overfit on the given task distribution and lack in generalization aspect. This begs the following question: How to effectively transfer image-level CLIP representations to videos? In this work, we show that a simple Video Fine-tuned CLIP (ViFi-CLIP) baseline is generally sufficient to bridge the domain gap from images to videos. Our qualitative analysis illustrates that the frame-level processing from CLIP image-encoder followed by feature pooling and similarity matching with corresponding text embeddings helps in implicitly modeling the temporal cues within ViFi-CLIP. Such fine-tuning helps the model to focus on scene dynamics, moving objects and inter-object relationships. For low-data regimes where full fine-tuning is not viable, we propose a `bridge and prompt' approach that first uses fine-tuning to bridge the domain gap and then learns prompts on language and vision side to adapt CLIP representations. We extensively evaluate this simple yet strong baseline on zero-shot, base-to-novel generalization, few-shot and fully supervised settings across five video benchmarks. Our code is available at https://github.com/muzairkhattak/ViFi-CLIP.Comment: Accepted at CVPR 202

Phytochemical screening and assessment of pharmacological properties of Swertia chirayita (Roxb. ex fleming) root methanolic extract

Background and Objective: Various parts of medicinal plants have been used to treat specific disorder from ancient times. Swertia chirayita (Roxb. ex Fleming) is a customary folklore medicine, used in the treatment of liver disorders, fevers, dysentery, diarrhea, stomach problems and other disorders. The present study was carried out in order to assess the antioxidant activity, to evaluate the antifungal properties of the plant’s root and to observe anticancer potential of methanolic extract of Swertia chirayita root. Materials and Methods: Phytochemical analysis and different chemical tests for the screening and identification of bioactive chemical constituents in Swertia chirayita methanolic root extract (SCME) were carried out using the standard procedures. The plants were purchased from local herbal market. In vitro determination of antioxidant properties of SCME were conducted using 1,1-diphenyl-2-picrylhydrazyl (DPPH)radical scavenging activity, H2O2 scavenging activity, Beta-carotene bleaching assay, total antioxidant activity by phosphomolybdenum method, azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging activity and hydroxyl radical scavenging activity. Anticancer activity of SCME was determined according to the protocol of brine shrimp lethality test. Antifungal potential was determined by measuring zone of inhibition on Potato Dextrose Agar (PDA) plates. The different concentrations of SCME used were 3.0, 1.5, 0.75 and 0.37 mg mL–1. The data were evaluated as Mean±Standard Deviations of 5 independent experimental responses. The results were analyzed using t-test for independent samples with SPSS version 16.0. Results: Phytochemical analysis of SCME showed that phlobatannins, tannins, saponins and terpenoids were present. The SCME exhibited strong antioxidant activity in a concentration dependent manner for in all six models. The SCME at dose of 3 mg mL–1 caused 100% death rate of brine shrimp after 72 h. The SCME showed potent activity against Aspergillus flavus (87%) followed by Aspergillus niger (88%) while the highest activity was shown against Aspergillus fumigatus (92%). Conclusion: The SCME exhibited strong antioxidant, antifungal and cytotoxic potential. Purification of different bioactive compounds should be carried out and in vivo studies are required for further verification.Scopu

First Class Futures: a Study of Update Strategies

Futures enable an efficient and easy to use programming paradigm for distributed applications. A natural way to benefit from distribution is to perform asynchronous invocations to methods or services. Upon invocation, a request is en-queued at the destination side and the caller can continue its execution. But a question remains: ``what if one wants to manipulate the result of an asynchronous invocation?'' First-class futures provide a transparent and easy-to-program answer: a future acts as the placeholder for the result of an asynchronous invocation and can be safely transmitted between processes while its result is not needed. Synchronization occurs automatically upon an access requiring the result. As references to futures disseminate, a strategy is necessary to propagate the result of each request to the processes that need it. This report studies the efficient transmission of results: it presents three main strategies in a semi-formal manner, and provides a cost analysis with some experiments to determine the efficiency of each strategy