479 research outputs found
Large mode area multi trench fiber for UV and visible transmission
No full textPlots of the figures in paper</span
Large mode area multi-trench fiber for UV and visible transmission
No full textWe experimentally demonstrate all-solid 10 and 20 µm core diameter multi-trench fibers for UV and visible wavelengths. Measurements ensure an effective single-mode operation over a wide range of bend radii, which is suitable for applications such as beam delivery. Both fibers were fabricated by the conventional modified chemical vapor deposition process, which is suitable for mass production. Moreover, all-solid fiber design ensures easy cleaving and splicing
Highly efficient Yb-free Er-La-Al doped ultra low NA large mode area single-trench fiber laser
No full text</span
Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers
No full textIn this paper, we report the mode area scaling of a rare-earth doped step index fiber by using low numerical aperture. Numerical simulations show the possibility of achieving an effective area of ~700µm2 (including bend induced effective area reduction) at a bend diameter of 32cm from a 35µm core fiber with a numerical aperture of 0.038. An effective single mode operation is ensured following the criterion of the fundamental mode loss to be lower than 0.1dB/m while ensuring the higher order modes loss to be higher than 10dB/m at a wavelength of 1060nm. Our optimized modified chemical vapor deposition process in conjunction with solution doping process allows fabrication of an Yb-doped step index fiber having an ultra-low numerical aperture of ~0.038. Experimental results confirm a Gaussian output beam from a 35µm core fiber validating our simulation results. Fiber shows an excellent laser efficiency of ~81% and a M2 less than 1.1
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Relational Care - with Mary Larkin and Manik Deepak-Gopinath [Podcast]
No full textWhat is 'relational care' and how can it improve the day-to-day experience of carers and those they care for? What are its implications for relationships between staff and service users in care settings? And how does the concept of relational care enable us to re-imagine the role of place and space in the experience of care? These are some of the questions we explore in this episode with Mary Larkin and Manik Deepak-Gopinath who recently completed a research project on the value and practice of relational care with older people.
Mary is Professor of Care, Carers and Caring at The Open University in the UK, where her research has focused on carers and caring and adult social care. She is the co-author, most recently of Family Carers and Caring, published in 2023 by Emerald. Manik is a Lecturer in Ageing, also at The Open University, and is a critical gerontologist with interests in the intersection of ageing, place and wellbeing, and in the intimate and family ties of older adults
My Name Is Deepak
No full textThis chapter looks at the author's responses to being given a nickname by his co-workers: Tupac. They do it in a friendly manner, but the author doesn’t understand the connection with the American rapper. It makes him think about who he is, his identity, and how people see him in his adopted country.</p
Sideffective - system to mine patient reviews: sentiment analysis
No full textSideffective is the system to crawl, rank and analyze patient testimonials about side ffeects from common medications. Since the wealth of any mining model is the Data corpus, the data collection phase involved extensive crawling of massive medical websites comprised of user forums from the internet. Subsequently, the raw files were subjected to certain site-specific parsing routines, yielding outputs conforming to a well-defined data model. Currently, the system holds close to 400,000 user testimonials pertaining to more than 2500 drugs/medicines. Sideffective aims at gathering and aggregating this wealth of information, build useful associations and present interesting observations and numeric validations, all in a user-friendly interface. The important issues that we have tried to tackle are: Extracting side effects without relying on pre-built lists, aggregating distribution of different side effect for a give drug, site-specific search, ranking and determining the negativity of reviews. The system has been jointly built by Deepak Yalamanchi and Sangeetha Rajagopalan under the guidance of Prof. Tomasz Imielinski. This thesis focuses mainly on Sentiment Analysis of patient reviews. While most existing sentiment analysis systems are predicated by POS (parts of speech) tagging or Bayesian sentiment analysis methods, the same cannot be applied to medical reviews as they generally carry a negative flavor in them. We thereby approached the problem by identifying the features in the sentence and calibrating the sentiment on a Negativity Meter based on their relation to sentiment words. A feature, as defined for the purpose of this thesis, can be a medicine, a side effect or a symptom. The sentiment of each feature is determined by the aggregate of all its polarities with respect to each sentiment word, where the polarity is determined by an inverse relation to the distance of the feature from the sentiment word. Each sentence is then evaluated by the cumulative polarity of all the features contained in it. Sentiment of a review is determined by individually determining the sentiment of each sentence and then getting a weighted sum score of all the sentences in the review. The accuracy of a sentiment analysis system is, in principle, how well it agrees with human judgments. Experimental results, involving human reviewers (extracted from site: www.askapatient.com) and correlating them back to the negativity rating of each review yield conclusive results, demonstrating the effectiveness of the technique. We have also implemented a customized Lucene search on the data using a multi-review summarization approach and a ranking scheme based on the feature-list. Ranking priority is given to the review that has the largest feature list size.M.S.Includes bibliographical referencesby Deepak Yalamanch
Hydrological niche segregation defines forest structure and drought tolerance strategies in a seasonal Amazon forest
No full textThe relationship between rooting depth and above‐ground hydraulic traits can potentially define drought resistance strategies that are important in determining species distribution and coexistence in seasonal tropical forests, and understanding this is important for predicting the effects of future climate change in these ecosystems. We assessed the rooting depth of 12 dominant tree species (representing c. 42% of the forest basal area) in a seasonal Amazon forest using the stable isotope ratios (δ18O and δ2H) of water collected from tree xylem and soils from a range of depths. We took advantage of a major ENSO‐related drought in 2015/2016 that caused substantial evaporative isotope enrichment in the soil and revealed water use strategies of each species under extreme conditions. We measured the minimum dry season leaf water potential both in a normal year (2014; Ψnon‐ENSO) and in an extreme drought year (2015; ΨENSO). Furthermore, we measured xylem hydraulic traits that indicate water potential thresholds trees tolerate without risking hydraulic failure (P50 and P88). We demonstrate that coexisting trees are largely segregated along a single hydrological niche axis defined by root depth differences, access to light and tolerance of low water potential. These differences in rooting depth were strongly related to tree size; diameter at breast height (DBH) explained 72% of the variation in the δ18Oxylem. Additionally, δ18Oxylem explained 49% of the variation in P50 and 70% of P88, with shallow‐rooted species more tolerant of low water potentials, while δ18O of xylem water explained 47% and 77% of the variation of minimum Ψnon‐ENSO and ΨENSO. We propose a new formulation to estimate an effective functional rooting depth, i.e. the likely soil depth from which roots can sustain water uptake for physiological functions, using DBH as predictor of root depth at this site. Based on these estimates, we conclude that rooting depth varies systematically across the most abundant families, genera and species at the Tapajós forest, and that understorey species in particular are limited to shallow rooting depths. Our results support the theory of hydrological niche segregation and its underlying trade‐off related to drought resistance, which also affect the dominance structure of trees in this seasonal eastern Amazon forest. Synthesis. Our results support the theory of hydrological niche segregation and demonstrate its underlying trade‐off related to drought resistance (access to deep water vs. tolerance of very low water potentials). We found that the single hydrological axis defining water use traits was strongly related to tree size, and infer that periodic extreme droughts influence community composition and the dominance structure of trees in this seasonal eastern Amazon forest
Highly efficient Yb-free Er-La-Al doped ultra low NA large mode area single-trench fiber laser
No full textWe demonstrate a 60µm core diameter Yb free Er-La-Al doped single-trench fiber having a 0.038 ultra-low-NA, fabricated using conventional MCVD process in conjunction with solution doping technique. Numerical simulations predict an effective single mode operation with effective area varying from 1,820µm2 to 1,960µm2 (taking bend-induced modal distortion into account) for different thicknesses of trenches and resonant rings at a constant bend radius of 25cm. Moreover, all solid structure favors easy cleaving and splicing. Experimental measurements demonstrate a robust effective single mode operation. Furthermore, with a 4%-4% laser cavity, this fiber shows a record efficiency of 46% with respect to the absorbed pump power
Building Thermal Performance Varies During Extreme Heat within Cities
No full textabstract: This document has been superseded by our peer-reviewed publication:
Building Thermal Performance, Climate Change, and Urban Heat Vulnerability, Matthew Nahlik, Mikhail Chester, Stephanie Pincetl, David Eisenman, Deepak Sivaraman, and Paul English, 2017, ASCE Journal of Infrastructure Systems, 23(3), doi:10.1061/(ASCE)IS.1943-555X.0000349
The publication is available at: http://dx.doi.org/10.1061/(ASCE)IS.1943-555X.0000349
The leading source of weather-related deaths in the United States is heat, and future projections show that the frequency, duration, and intensity of heat events will increase in the Southwest. Presently, there is a dearth of knowledge about how infrastructure may perform during heat waves or could contribute to social vulnerability. To understand how buildings perform in heat and potentially stress people, indoor air temperature changes when air conditioning is inaccessible are modeled for building archetypes in Los Angeles, California, and Phoenix, Arizona, when air conditioning is inaccessible is estimated. An energy simulation model is used to estimate how quickly indoor air temperature changes when building archetypes are exposed to extreme heat. Building age and geometry (which together determine the building envelope material composition) are found to be the strongest indicators of thermal envelope performance. Older neighborhoods in Los Angeles and Phoenix (often more centrally located in the metropolitan areas) are found to contain the buildings whose interiors warm the fastest, raising particular concern because these regions are also forecast to experience temperature increases. To combat infrastructure vulnerability and provide heat refuge for residents, incentives should be adopted to strategically retrofit buildings where both socially vulnerable populations reside and increasing temperatures are forecast
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