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18 result(s) for "Porterfield, Katherine"
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Forecasting influenza-like illness dynamics for military populations using neural networks and social media
This work is the first to take advantage of recurrent neural networks to predict influenza-like illness (ILI) dynamics from various linguistic signals extracted from social media data. Unlike other approaches that rely on timeseries analysis of historical ILI data and the state-of-the-art machine learning models, we build and evaluate the predictive power of neural network architectures based on Long Short Term Memory (LSTMs) units capable of nowcasting (predicting in \"real-time\") and forecasting (predicting the future) ILI dynamics in the 2011 - 2014 influenza seasons. To build our models we integrate information people post in social media e.g., topics, embeddings, word ngrams, stylistic patterns, and communication behavior using hashtags and mentions. We then quantitatively evaluate the predictive power of different social media signals and contrast the performance of the-state-of-the-art regression models with neural networks using a diverse set of evaluation metrics. Finally, we combine ILI and social media signals to build a joint neural network model for ILI dynamics prediction. Unlike the majority of the existing work, we specifically focus on developing models for local rather than national ILI surveillance, specifically for military rather than general populations in 26 U.S. and six international locations., and analyze how model performance depends on the amount of social media data available per location. Our approach demonstrates several advantages: (a) Neural network architectures that rely on LSTM units trained on social media data yield the best performance compared to previously used regression models. (b) Previously under-explored language and communication behavior features are more predictive of ILI dynamics than stylistic and topic signals expressed in social media. (c) Neural network models learned exclusively from social media signals yield comparable or better performance to the models learned from ILI historical data, thus, signals from social media can be potentially used to accurately forecast ILI dynamics for the regions where ILI historical data is not available. (d) Neural network models learned from combined ILI and social media signals significantly outperform models that rely solely on ILI historical data, which adds to a great potential of alternative public sources for ILI dynamics prediction. (e) Location-specific models outperform previously used location-independent models e.g., U.S. only. (f) Prediction results significantly vary across geolocations depending on the amount of social media data available and ILI activity patterns. (g) Model performance improves with more tweets available per geo-location e.g., the error gets lower and the Pearson score gets higher for locations with more tweets.
Plastic contamination of composts derived from feedstocks with and without food waste
Plastic has become a prominent material type used for numerous purposes since the 1950s and persists in waterbodies, sediments, and terrestrial soils worldwide. Through time, plastics break apart into smaller fragments that become dispersed throughout the environment. Organic waste derived soil amendments, such as compost, may serve as a transport vector for plastics into terrestrial soils. A Vermont-wide survey was conducted to provide a range of plastic abundance, mass, and types found in composts and contextualize future research on plastic effects. Twenty composts were analyzed including composts derived from feedstocks with both high (15% or more by volume) and low/no (5% or less by volume) food waste inclusion. Plastics were isolated in multiple size classes (> 5 mm, 1–5 mm, and 0.5–1 mm) with sieving, 30% hydrogen peroxide digestion, and microscopy. Fourier transform infrared (FTIR) spectrum similarity was also used to identify plastic polymers. Ranges of 0 to 1,201 plastic particles per dry kg of compost and 0 to 0.056% w/w plastic contamination on a dry mass basis were found across the composts. Plastic abundance was not a predictor of plastic mass. No statistical differences were found between the high and low/no food waste compost groups due to variability and relatively low sample sizes, although the five most contaminated composts (> 0.02% w/w) were all in the high food waste group. Methodological challenges and recommendations are also discussed, including emphasis on establishing confidence levels for putative microplastic confirmation under the uncertainty that is inherent to analyzing complex organic matrices using microscopy and FTIR.
Toward Zero Hunger Through Coupled Ecological Sanitation-Agriculture Systems
Ecological sanitation (EcoSan) systems capture and sanitize human excreta and generate organic nutrient resources that can support more sustainable nutrient management in agricultural ecosystems. An emerging EcoSan system that is implemented in Haiti and several other contexts globally couples container-based household toilets with aerobic, thermophilic composting. This closed loop sanitation system generates organic nutrient resources that can be used as part of an ecological approach to soil nutrient management and thus has the potential to contribute to Sustainable Development Goals 2 (zero hunger), 6 (clean water and sanitation for all), and 13 (climate change solutions). However, the role of organic nutrient resources derived from human excreta in food production is poorly studied. We conducted a greenhouse experiment comparing the impact of feces-derived compost on crop production, soil nutrient cycling, and nutrient losses with two amendments produced from wastewater treatment (pelletized biosolids and biofertilizer), urea, and an unfertilized control. Excreta-derived amendments increased crop yields 2.5 times more than urea, but had differing carry-over effects. After a one-time application of compost, crop production remained elevated throughout all six crop cycles. In contrast, the carry-over of crop response lasted two and four crop cycles for biosolids and biofertilizer, respectively, and was absent for urea. Soil carbon concentration in the compost amended soils increased linearly through time from 2.0 to 2.5%, an effect not seen with other treatments. Soil nitrous oxide emissions factors ranged from 0.3% (compost) to 4.6% (biosolids), while nitrogen leaching losses were lowest for biosolids and highest for urea. These results indicate that excreta-derived compost provides plant available nutrients, while improving soil health through the addition of soil organic carbon. It also improved biogeochemical functions, indicating the potential of excreta-derived compost to close nutrient loops if implemented at larger scales. If captured and safely treated through EcoSan, human feces produced in Haiti can meet up to 13, 22, and 11% of major crop needs of nitrogen, phosphorus, and potassium, respectively.
Upcycling Phosphorus Recovered from Anaerobically Digested Dairy Manure to Support Production of Vegetables and Flowers
Dissolved air flotation (DAF) separates phosphorus (P)-rich fine solids from anaerobically digested dairy manure, creating opportunities to export surplus P to the marketplace as a bagged plant food product. Seedlings of tomato and marigold were amended at various volume per volume (v/v) ratios with plant foods consisting of fine solids upcycled (i.e., transformed into a higher quality product) by drying and blending with other organic residuals. A plate competition assay was conducted to assess the fine solids’ potential to suppress the plant pathogen Rhizoctonia solani. Plant foods were comprised of 2.0–2.1% N, 0.8–0.9% P and 0.6–0.8% K. Extractions indicated that plant foods contained a mixture of plant-available and slow-release P. At 6% v/v plant food, dry biomass of marigold and tomato were six-times greater than the unamended control and not significantly different from a market alternative treatment. Fine solids exhibited negligible potential to suppress R. solani. This study indicates that DAF-separated fine solids could be used to support horticulture, providing information for design of a circular economy approach to dairy manure nutrient management. Life cycle assessment and business model development for this nutrient recovery strategy are necessary next steps to further guide sustainability efforts.
Healing in forgiveness: A discussion with Amanda Lindhout and Katherine Porterfield, PhD
In 2008, Amanda Lindhout was kidnapped by a group of extremists while traveling as a freelance journalist in Somalia. She and a colleague were held captive for more than 15 months, released only after their families paid a ransom. In this interview, Amanda discusses her experiences in captivity and her ongoing recovery from this experience with Katherine Porterfield, Ph.D. a clinical psychologist at the Bellevue/NYU Program for Survivors of Torture. Specifically, Amanda describes the childhood experiences that shaped her thirst for travel and knowledge, the conditions of her kidnapping, and her experiences after she was released from captivity. Amanda outlines the techniques that she employed to survive in the early aftermath of her capture, and how these coping strategies changed as her captivity lengthened. She reflects on her transition home, her recovery process, and her experiences with mental health professionals. Amanda's insights provide an example of resilience in the face of severe, extended trauma to researchers, clinicians, and survivors alike. The article ends with an discussion of the ways that Amanda's coping strategies and recovery process are consistent with existing resilience literature. Amanda's experiences as a hostage, her astonishing struggle for physical and mental survival, and her life after being freed are documented in her book, co-authored with Sara Corbett, A House in the Sky.
Upcycling Dairy Manure Fine Solids Captured by Dissolved Air Flotation as Part of a Phosphorus Recovery and Reuse Strategy
Dissolved air flotation (DAF) has shown potential to substantially improve phosphorus (P) mass balance on dairy farms by capturing P associated with fine solids from liquid manure, enabling new management options. However, at < 25% total solids, further dewatering and other upcycling is necessary to facilitate export of recovered fine solids off farm for use in bagged or bulk products. I generated plant foods using DAF-captured dairy manure fine solids thermally dried to 45% total solids blended with other organic residuals. Dry biomass of tomato and marigold seedlings amended with 6% v/v plant food was six-times greater than the unamended control and not significantly different from a market alternative treatment. Because thermal dewatering can be prohibitively costly, I generated a second batch of plant foods using DAF-captured dairy manure fine solids conditioned with 3, 4.5 and 6% (w/w) quicklime or lime kiln dust (LKD) and dewatered using a benchtop press for comparison with thermally dried fine solids. Tomato seedling biomass was similar for thermally dried and LKD plant foods, but quicklime plant foods had no effect compared to the unamended control. Quicklime and LKD conditioned fine solids contained approximately 30 and 10 times less plant-available P than thermally dried fine solids, respectively—likely due to precipitation of Ca-P minerals. These studies indicate that DAF-captured dairy manure fine solids could be upcycled to bagged horticultural products with substantial agronomic value, however sustainable materials drying remains a key challenge to realizing this potential.
Meeting the Needs of Parentally Bereaved Children: A Framework for Child-Centered Parenting
This article describes the development and deployment of a framework for measuring parenting capacities in the context of bereavement. Grounded theoretical analysis of interviews with a community sample of 41 bereaved spouses with school-aged children elicited a set of nine bereavement-specific parenting tasks. A corollary coding system (covering all nine parenting tasks) was created to transform interview materials into quantitative data, thus permitting systematic empirical investigation of the parenting capacities of bereaved spouses. Parenting behaviors were coded on a 5-point scale ranging from least child-centered to most child-centered. Sex of surviving parent and circumstances of death proved to be significant mediating variables: mothers were more child-centered than fathers, and parents surviving sudden deaths more child-centered than those surviving anticipated deaths. Lengthy illness was associated with less child-centered parenting. The more child-centered the parenting, the less symptomatic the child as measured by parent report (Child Behavior Checklist) and child self-report (Children's Depression Inventory, Revised Child Manifest Anxiety Scale). Child-centered parenting was associated with more positive and fewer negative perceptions of the surviving parent by the child as measured by the Parent Perception Inventory. Implications of findings are discussed.
Managing Traumatic Stress in Children Anticipating Parental Death
Qualitative evidence drawn from a community study of 58 parentally bereaved school-age children and their surviving parents provides a descriptive exploration of one of the most difficult challenges faced by families in anticipated deaths: managing the stress of a child's exposure to the graphic physical, emotional, and mental deterioration of the dying parent. The concept of traumatic stress is broadly defined to include exposure to the \"fact\" of impending death itself, that is, the anxiety that comes from knowing that one may lose a close other. Included, as well, is an exploration of secondary traumatic stress, defined here to cover the notion of the stress of watching other loved ones in the family succumb to terror and anxiety about the impending death. Emphasis is placed on a child's unique vulnerability to traumatic stressors and on the role of parenting in mediating child exposure to parental decline. In contrast to the anticipatory grief literature which emphasizes the advantages of forewarning in cushioning postmortem adjustment, this study documents the adverse impact of a child's exposure to graphic stimuli. These findings underscore the need for clinicians to attend to the traumatic stress of \"ordinary\" anticipated deaths, rather than maintaining an exclusive grief orientation.
A Chronological Edge-Driven Approach to Temporal Subgraph Isomorphism
Many real world networks are considered temporal networks, in which the chronological ordering of the edges has importance to the meaning of the data. Performing temporal subgraph matching on such graphs requires the edges in the subgraphs to match the order of the temporal graph motif we are searching for. Previous methods for solving this rely on the use of static subgraph matching to find potential matches first, before filtering them based on edge order to find the true temporal matches. We present a new algorithm for temporal subgraph isomorphism that performs the subgraph matching directly on the chronologically sorted edges. By restricting our search to only the subgraphs with chronologically correct edges, we can improve the performance of the algorithm significantly. We present experimental timing results to show significant performance improvements on publicly available datasets for a number of different temporal query graph motifs with four or more nodes. We also demonstrate a practical example of how temporal subgraph isomorphism can produce more meaningful results than traditional static subgraph searches.