Role of Radiotherapy in the Management of Pancreatic Adenocarcinoma: Debate and Discordance in Clinical Trials

Pancreatic adenocarcinoma (PAC) is an extremely fatal malignancy with dismal outcome with standard treatment till date. Investigators are constantly in search of optimal treatment approach and radiation therapy (RT) remains in the centre of debate. Human pancreatic cancer cell lines have shown both intrinsic and hypoxia induced radio resistance, and RT has produced conflicting results as well in the various clinical trials. However, most of the American studies continued the use of RT as a potential treatment modality but the European school of thought is widely criticized for their ‘therapeutic nihilism’ towards radiation and faulty clinical trial designs. This article has reviewed the available literature on the evolving role of RT for the management of resectable and borderline resectable PAC and has highlighted the increasing trend towards the use of radiotherapy for both adjuvant and neo adjuvant treatment. With the advent of modern RT techniques, the acute and late toxicities are much less than the earlier time, and therefore augmented RT is expected to produce better clinical outcomes for the patients with pancreatic carcinoma.

A PROSPECTIVE COMPARATIVE STUDY ON LOCALLY ADVANCED RECTAL CARCINOMA TREATED WITH PRE-OPERATIVE SHORT-COURSE RADIOTHERAPY VERSUS LONG-COURSE RADIOTHERAPY WITH CONCOMITANT CHEMOTHERAPY

Objective: In locally advanced non-metastatic rectal carcinoma, pre-operative radiotherapy is an acceptable alternative over post-operative radiation to improve locoregional control after radical surgery. There are two regimens of pre-operative radiotherapy – short-course radiotherapy (25 Gy/5 fractions/1 week) and long-course chemoradiotherapy (CRT) (50.4 Gy/28 fractions/5.5 weeks). Our study aimed to compare the pathological response, margin negative surgery rates, and treatment-related acute toxicities between these two approaches. Methods: Patients with histologically proven locally advanced, non-metastatic rectal adenocarcinoma were randomized into study group and control group – the study group received short-course radiotherapy (25 Gy/5 fractions/1 week) followed by surgery after 7–10 days of completion of radiotherapy and the control group received long-course radiotherapy (50.4 Gy/28 fractions/5.5 weeks) with concurrent capecitabine followed by surgery after 4–6 weeks of completion of radiotherapy. Histopathology reports were studied in both groups for the determination of pathological response of tumor and surgical margin status. All patients received adjuvant chemotherapy for 6 months with oxaliplatin and capecitabine. For the assessment of treatment-related acute toxicities, patients were examined during the entire course of treatment. Results: Overall pathological response (complete response+partial response) was 81.25% in the study arm and 86.66% in the control arm. Complete response rate was 15% in the study arm and 25% in the control arm. Margin negative surgery rates were higher in long-course CRT than short-course radiotherapy (90% vs. 82%), but it was statistically insignificant. Radiation-induced acute skin reactions (less than Grade 2) were significantly higher in long-course CRT arm (p=0.003). Conclusion: There is no significant difference between pre-operative short-course radiotherapy and long-course concomitant CRT in terms of efficacy and acute toxicity profile. Thus, with our limited resources and huge patient load, short-course radiotherapy can be used as an acceptable alternative to long-course CRT

A comparative property investigation of lithium phosphate glass melted in microwave and conventional heating

The present study addresses the application of microwave (MW) energy for melting lithium phosphate glass. A comparative analysis of the properties is presented with glasses melted in conventional resistance heating adopting standard methods of characterization. The density of the glass was found less in MW heating. The glass transition temperature was recorded as 3–10◦C lower in MW prepared glass than in conventional glass. Micro-hardness is found to be improved in case of MW heating. Maximum forward power was recorded less than 2 kW with an average power ∼1kW during melting of 40g glass in MW furnace. MW forward and reflected power measured during melting in the MW cavity was elaborated. Total melting time was within 2h 30 min in MW heating, whereas it was 6–7 h in resistive heating. Total power consumed was ∼5kWh in MW heating and ∼14kWh in resistance heating

Crop biophysical parameter retrieval from Sentinel-1 SAR data with a multi-target inversion of Water Cloud Model

Estimation of bio-and geophysical parameters from Earth observation (EO) data is essential for developing applications on crop growth monitoring. High spatio-temporal resolution and wide spatial coverage provided by EO satellite data are key inputs for operational crop monitoring. In Synthetic Aperture Radar (SAR) applications, a semi-empirical model (viz., Water Cloud Model (WCM)) is often used to estimate vegetation descriptors individually. However, a simultaneous estimation of these vegetation descriptors would be logical given their inherent correlation, which is seldom preserved in the estimation of individual descriptors by separate inversion models. This functional relationship between biophysical parameters is essential for crop yield models, given that their variations often follow different distribution throughout crop development stages. However, estimating individual parameters with independent inversion models presume a simple relationship (potentially linear) between the biophysical parameters. Alternatively, a multi-target inversion approach would be more effective for this aspect of model inversion compared to an individual estimation approach. In the present research, the multi-output support vector regression (MSVR) technique is used for inversion of the WCM from C-band dual-pol Sentinel-1 SAR data. Plant Area Index (PAI, m2 m−2) and wet biomass (W, kg m−2) are used as the vegetation descriptors in the WCM. The performance of the inversion approach is evaluated with in-situ measurements collected over the test site in Manitoba (Canada), which is a super-site in the Joint Experiment for Crop Assessment and Monitoring (JECAM) SAR inter-comparison experiment network. The validation results indicate a good correlation with acceptable error estimates (normalized root mean square error–nRMSE and mean absolute error–MAE) for both PAI and wet biomass for the MSVR approach and a better estimation with MSVR than single-target models (support vector regression–SVR). Furthermore, the correlation between PAI and wet biomass is assessed using the MSVR and SVR model. Contrary to the single output SVR, the correlation between biophysical parameters is adequately taken into account in MSVR based simultaneous inversion technique. Finally, the spatio-temporal maps for PAI and W at different growth stages indicate their variability with crop development over the test site.This research was supported in part by Shastri Indo-Candian Institute, New Delhi, India and the Spanish Ministry of Economy, Industry and Competitiveness, in part by the State Agency of Research (AEI), in part by the European Funds for Regional Development under project TEC2017-85244-C2-1-P

Novel clustering schemes for full and compact polarimetric SAR data: An application for rice phenology characterization

Information on rice phenological stages from Synthetic Aperture Radar (SAR) images is of prime interest for in-season monitoring. Often, prior in-situ measurements of phenology are not available. In such situations, unsupervised clustering of SAR images might help in discriminating phenological stages of a crop throughout its growing period. Among the existing unsupervised clustering techniques using full-polarimetric (FP) SAR images, the eigenvalue-eigenvector based roll-invariant scattering-type parameter, and the scattering entropy parameter are widely used in the literature. In this study, we utilize a unique target scattering-type parameter, which jointly uses the Barakat degree of polarization and the elements of the polarimetric coherency matrix. Likewise, we also utilize an equivalent parameter proposed for compact-polarimetric (CP) SAR data. These scattering-type parameters are analogous to the Cloude-Pottier’s parameter for FP SAR data and the ellipticity parameter for CP SAR data. Besides this, we also introduce new clustering schemes for both FP and CP SAR data for segmenting diverse scattering mechanisms across the phenological stages of rice. In this study, we use the RADARSAT-2 FP and simulated CP SAR data acquired over the Indian test site of Vijayawada under the Joint Experiment for Crop Assessment and Monitoring (JECAM) initiative. The temporal analysis of the scattering-type parameters and the new clustering schemes help us to investigate detailed scattering characteristics from rice across its phenological stages.This work was supported in part by the Spanish Ministry of Science, Innovation and Universities, the State Agency of Research (AEI), and the European Funds for Regional Development (EFRD) under Project TEC 2017-85244-C 2-1-P. The work of Dipankar Mandal was supported by the Ministry of Human Resource Development, Government of India (New Delhi, India) towards his Ph.D. assistantship through grant no. RSPHD0210

Dual polarimetric radar vegetation index for crop growth monitoring using sentinel-1 SAR data

Sentinel-1 Synthetic Aperture Radar (SAR) data have provided an unprecedented opportunity for crop monitoring due to its high revisit frequency and wide spatial coverage. The dual-pol (VV-VH) Sentinel-1 SAR data are being utilized for the European Common Agricultural Policy (CAP) as well as for other national projects, which are providing Sentinel derived information to support crop monitoring networks. Among the Earth observation products identified for agriculture monitoring, indicators of vegetation status are deemed critical by end-user communities. In literature, several experiments usually utilize the backscatter intensities to characterize crops. In this study, we have jointly utilized the scattering information in terms of the degree of polarization and the eigenvalue spectrum to derive a new vegetation index from dual-pol (DpRVI) SAR data. We assess the utility of this index as an indicator of plant growth dynamics for canola, soybean, and wheat, over a test site in Canada. A temporal analysis of DpRVI with crop biophysical variables (viz., Plant Area Index (PAI), Vegetation Water Content (VWC), and dry biomass (DB)) at different phenological stages confirms its trend with plant growth dynamics. For each crop type, the DpRVI is compared with the cross and co-pol ratio (σVH0/σVV0) and dual-pol Radar Vegetation Index (RVI = 4σVH0/(σVV0 + σVH0)), Polarimetric Radar Vegetation Index (PRVI), and the Dual Polarization SAR Vegetation Index (DPSVI). Statistical analysis with biophysical variables shows that the DpRVI outperformed the other four vegetation indices, yielding significant correlations for all three crops. Correlations between DpRVI and biophysical variables are highest for canola, with coefficients of determination (R2) of 0.79 (PAI), 0.82 (VWC), and 0.75 (DB). DpRVI had a moderate correlation (R2≳ 0.6) with the biophysical parameters of wheat and soybean. Good retrieval accuracies of crop biophysical parameters are also observed for all three crops.This work was supported by the Spanish Ministry of Science, Innovation and Universities, the State Agency of Research (AEI) and the European Funds for Regional Development (EFRD) under Project TEC2017-85244-C2-1-P

A Novel Phenology Based Feature Subset Selection Technique Using Random Forest for Multitemporal PolSAR Crop Classification

Feature selection techniques intent to select a subset of features that minimizes redundancy and maximizes relevancy for classification problems in machine learning. Standard methods for feature selection in machine learning seldom take into account the domain knowledge associated with the data. Multitemporal crop classification studies with full-polarimetric synthetic aperture radar (PolSAR) data ought to consider the changes in the scattering mechanisms with their phenological growth stages. Hence, it is desirable to incorporate these changes while determining a feature subset for classification. In this study, a random forest (RF) based feature selection technique is proposed that takes into account the changes in the physical scattering mechanism with crop phenological stages for multitemporal PolSAR classification. The partial probability plot, which is an attribute of RF, provides information about the marginal effect of a polarimetric parameter on the desired crop class. Moreover, it is used to identify the specific range of a parameter where the probability of the presence of a particular crop class is high. The proposed technique identifies features that change significantly with crop phenology. The selected features are the ones whose ranges show maximum separation amongst crop classes. Additionally, the feature subset is refined by eliminating correlated features. The E-SAR L-band dataset of the AgriSAR-2006 campaign over the Demmin test site in Germany is used in this study. The classification accuracy using the novel feature selection technique is 99.12%. This is nominally better than using the features obtained from a standard feature selection method used in RF, such as mean decrease Gini (98.73%) and mean decrease accuracy (98.68%) that do not take into account the information based on crop phenology.This work was supported in part by the Spanish Ministry of Economy, Industry and Competitiveness, in part by the State Agency of Research (AEI), and in part by the European Funds for Regional Development under Projects TIN2014-55413-C2-2-P and TEC2017-85244-C2-1-P

Roadmap on chalcogenide photonics

Alloys of sulfur, selenium and tellurium, often referred to as chalcogenide semiconductors, offer a highly versatile, compositionally-controllable material platform for a variety of passive and active photonic applications. They are optically nonlinear, photoconductive materials with wide transmission windows that present various high- and low-index dielectric, low-epsilon and plasmonic properties across ultra-violet, visible and infrared frequencies, in addition to an, non-volatile, electrically/optically induced switching capability between phase states with markedly different electromagnetic properties. This roadmap collection presents an in-depth account of the critical role that chalcogenide semiconductors play within various traditional and emerging photonic technology platforms. The potential of this field going forward is demonstrated by presenting context and outlook on selected socio-economically important research streams utilizing chalcogenide semiconductors. To this end, this roadmap encompasses selected topics that range from systematic design of material properties and switching kinetics to device-level nanostructuring and integration within various photonic system architectures

Prediction of 3-D structures of fucose-binding proteins and structural analysis of their interaction with ligands

The importance of fucose-binding proteins stems from the presence of fucose as terminal sugars in H and Lewis (a) blood groups. Recently, the structure of a complex between Anguilla anguilla agglutinin (AAA) and α-L-fucose has been worked out at 1.9 A resolution. The structure of AAA characterizes the novel fold of an entire lectin family. In the present study, molecular modeling techniques have been used to identify new proteins that can provide a similar fucose binding module in the newly discovered genomic sequences using the above mentioned structural information.We modeled 3-D structures of three such proteins, namely, ebiP5322 protein of Anopheles gambiae, a pentraxin of Xenopus laevis, and the fw gene product of Drosophila melanogaster. α-L-fucose was docked in the binding pockets of the modeled structures followed by energy minimization and molecular dynamic runs to obtain the most probable structures of the complexes. Properties of these modeled complexes were studied to examine the nature of physicochemical forces involved in the complex formation and compared with AAA-α-L-fucose complex. It was found that ebiP5322 protein of A. gambiae and the pentraxin of X. laevis can provide a fucose-binding fold similar to AAA.We studied structures of four protein-fucose complexes to examine the electrostatic potential surfaces around the binding site and concluded that a highly positive-charged surface was not a necessary condition of fucose-binding