UMBC Faculty Collection

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Periodic Gamma-Ray Modulation of the Blazar PG 1553+113 Confirmed by Fermi-LAT and Multiwavelength Observations
(IOP, 2024-11-25) Abdollahi, S.; Baldini, L.; Barbiellini, G.; Bellazzini, R.; Berenji, B.; Bissaldi, E.; Blandford, R. D.; Bonino, R.; Bruel, P.; Buson, S.; Cameron, R. A.; Caraveo, P. A.; Casaburo, F.; Cavazzuti, E.; Cheung, C. C.; Chiaro, G.; Ciprini, S.; Cozzolongo, G.; Orestano, P. Cristarella; Cutini, S.; D’Ammando, F.; Lalla, N. Di; Dirirsa, F.; Venere, L. Di; Domínguez, A.; Fegan, S. J.; Ferrara, E. C.; Fiori, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Garrappa, S.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Green, D.; Grenier, I. A.; Guiriec, S.; Hays, E.; Horan, D.; Kuss, M.; Larsson, S.; Laurenti, M.; Li, J.; Liodakis, I.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Maldera, S.; Malyshev, D.; Manfreda, A.; Marcotulli, L.; Martí-Devesa, G.; Mazziotta, M. N.; Mereu, I.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Negro, M.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J. F.; Paneque, D.; Perri, M.; Persic, M.; Pesce-Rollins, M.; Porter, T. A.; Principe, G.; Rainò, S.; Rando, R.; Rani, Bindu; Razzano, M.; Reimer, A.; Reimer, O.; Parkinson, P. M. Saz; Scotton, L.; Serini, D.; Sesana, A.; Sgrò, C.; Siskind, E. J.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, M. N.; Tak, D.; Thayer, J. B.; Thompson, D. J.; Torres, D. F.; Valverde, Janeth; Verrecchia, F.; Zaharijas, G.
A 2.1 yr periodic oscillation of the gamma-ray flux from the blazar PG 1553+113 has previously been tentatively identified in ?7 yr of data from the Fermi Large Area Telescope. After 15 yr of Fermi sky-survey observations, doubling the total time range, we report >7 cycle gamma-ray modulation with an estimated significance of 4? against stochastic red noise. Independent determinations of oscillation period and phase in the earlier and the new data are in close agreement (chance probability <0.01). Pulse timing over the full light curve is also consistent with a coherent periodicity. Multiwavelength new data from Swift X-Ray Telescope, Burst Alert Telescope, and UVOT, and from KAIT, Catalina Sky Survey, All-Sky Automated Survey for Supernovae, and Owens Valley Radio Observatory ground-based observatories as well as archival Rossi X-Ray Timing Explorer satellite-All Sky Monitor data, published optical data of Tuorla, and optical historical Harvard plates data are included in our work. Optical and radio light curves show clear correlations with the gamma-ray modulation, possibly with a nonconstant time lag for the radio flux. We interpret the gamma-ray periodicity as possibly arising from a pulsational accretion flow in a sub-parsec binary supermassive black hole system of elevated mass ratio, with orbital modulation of the supplied material and energy in the jet. Other astrophysical scenarios introduced include instabilities, disk and jet precession, rotation or nutation, and perturbations by massive stars or intermediate-mass black holes in polar orbit.
Mathematics Discourse in Secondary Teacher Candidates’ Lessons: A Mixed Methods Analysis
(MDPI, 2024-11-25) Schmidt, Ashley; Rakes, Christopher; Bush, Sarah B.; Ronau, Robert N.; Soni, Siddhi; Fisher, Molly; Amick, Lisa; Viera, Julian; Safi, Farshid
(1) Background: Meaningful discourse in the mathematics classroom involves creating a learning community that empowers students to articulate their reasoning and make sense of the contributions of their peers while advancing the learning of mathematics for the entire class. This study assessed the degree to which secondary mathematics (Grades 7–12) teacher candidates incorporated discourse into their lessons and the factors influencing their decisions. (2) Methods: An explanatory mixed methods design was used, in which data were collected sequentially. Lesson videos were analyzed, followed by interviews of teacher candidates with high-discourse lessons. (3) Results: This study found that participants showed significant growth in their use of effective teaching practices from the beginning of the semester to the end of the semester, including mathematics discourse. The interviews revealed four contributing factors: intentional effort, learning experiences, professional relationships, and pedagogical knowledge. (4) Conclusions: Understanding the experiences of teacher candidates during their own learning of mathematics, their mathematical identities, and beliefs about mathematics could help generate knowledge regarding the implementation of mathematics discourse and other reform-based practices in teacher instruction.
An Investigation of the Relationship Between Crime Rate and Police Compensation
(2024-11-21) Amarsingh, Jhancy; Appakondreddigari, Likhith Kumar Reddy; Nunna, Ashish; Tummala, Charishma Choudary; Winship, John; Zhou, Alex; Ashqar, Huthaifa
The goal of this paper is to assess whether there is any correlation between police salaries and crime rates. Using public data sources that contain Baltimore Crime Rates and Baltimore Police Department (BPD) salary information from 2011 to 2021, our research uses a variety of techniques to capture and measure any correlation between the two. Based on that correlation, the paper then uses established social theories to make recommendations on how this data can potentially be used by State Leadership. Our initial results show a negative correlation between salary/compensation levels and crime rates.
Remote Sensing of Ice Cloud Properties With Millimeter and Submillimeter-Wave Polarimetry
(IEEE, 2024-11-20) Wu, Dong L.; Gong, Jie; Deal, William R.; Gaines, Willian; Cooke, Caitlyn M.; De Amici, Giovanni; Pantina, Peter; Liu, Yuli; Yang, Ping; Eriksson, Patrick; Bennartz, Ralf
Ice clouds are poorly constrained in current global climate and weather models and have been used as a tuning parameter in the models to balance radiation budget at the top of atmosphere and precipitation at the surface. Sub-millimeter-wave (Submm) remote sensing can fill the sensitivity gap of cloud ice observations between visible/infrared (VIS/IR) and microwave (MW) frequencies. The added value from submm-wave bands has been recognized for achieving a better understanding of cloud, convection and precipitation (CCP) processes. Recent satellite observations at microwave frequencies showed promising results that additional information on cloud microphysical properties (e.g., ice particle shape and orientation) can be inferred from V-pol and H-pol radiances. Motivated by the added value from cloud polarimeters, a compact SWIRP (Submm-Wave and Long-Wave InfraRed Polarimeter) was developed under NASA's Instrument Incubator Program (IIP) to reduce instrument size, weight, power (SWaP) for future Earth science missions. Low-SWaP sensors like SWIRP will allow the cost-effective implementation of a distributed observing system to study fast cloud processes with the needed spatiotemporal sampling.
Listening for Expert Identified Linguistic Features: Assessment of Audio Deepfake Discernment among Undergraduate Students
(2024-11-21) Bhalli, Noshaba Nasir; Naqvi, Nehal; Evered, Chloe; Mallinson, Christine; Janeja, Vandana
This paper evaluates the impact of training undergraduate students to improve their audio deepfake discernment ability by listening for expert-defined linguistic features. Such features have been shown to improve performance of AI algorithms; here, we ascertain whether this improvement in AI algorithms also translates to improvement of the perceptual awareness and discernment ability of listeners. With humans as the weakest link in any cybersecurity solution, we propose that listener discernment is a key factor for improving trustworthiness of audio content. In this study we determine whether training that familiarizes listeners with English language variation can improve their abilities to discern audio deepfakes. We focus on undergraduate students, as this demographic group is constantly exposed to social media and the potential for deception and misinformation online. To the best of our knowledge, our work is the first study to uniquely address English audio deepfake discernment through such techniques. Our research goes beyond informational training by introducing targeted linguistic cues to listeners as a deepfake discernment mechanism, via a training module. In a pre-/post- experimental design, we evaluated the impact of the training across 264 students as a representative cross section of all students at the University of Maryland, Baltimore County, and across experimental and control sections. Findings show that the experimental group showed a statistically significant decrease in their unsurety when evaluating audio clips and an improvement in their ability to correctly identify clips they were initially unsure about. While results are promising, future research will explore more robust and comprehensive trainings for greater impact.
Visualization for Cyber Complex Systems: Application, Issues and Future Work
(2024) Nikolov, Georgi; Varga, Margaret; Träber-Burdin, Susan; Winkelholz, Carsten; Kullman, Kaur; Lavigne, Valérie
Technology advances at a rapid pace; new components are being developed, offering opportunities to create even more intricate networks of devices, interconnected on both local and global scale, offering ever faster processing while generating vast amounts of data. Technological advancements facilitate improvements for individuals’ daily lives, our work environment, societal enhancements, military defense capabilities, etc. Unfortunately, when an issue manifests in these new networks, it is often difficult to immediately identify the origin and apply an appropriate solution in a timely fashion. The infrastructure built to sustain our society’s needs has become complicated and interconnected, evolving into a complex system rather than a complicated one. Complex systems are difficult to manage without an in-depth knowledge of the underlying components and their interactions - where the whole is greater than the sum of its parts. To aid in this task, new ways to visualize such a system of systems need to be developed to represent them accordingly and enable its operators to identify problems and apply actionable solutions. In this paper, we offer a detailed explanation on what complex systems are, the difficulty of maintaining actionable situational awareness and understanding, and how Visual Analytics and Data Visualization can help in resolving some of these issues. Examples of visual representations will be discussed, together with techniques used for their evaluations in terms of their usefulness and usability. Finally, a brief overview of possible future advancements that can support better understanding and management of complex systems will be discussed.
Interactive Assessment of Variances of High-Resolution Model Features in Digital Twin Simulations
(ACM, 2024-11-22) Kulkarni, Chhaya; Privé, Nikki; Janeja, Vandana
Prior to the deployment of expensive instruments into orbit, spatio-temporal digital twin systems modeling the whole earth are used to study the efficacy of these instruments. However, we need to make sure that the simulated instruments have realistic characteristics (to reflect the physics of the atmosphere and limits of the instrument itself) in order for the results of the digital twin to be robust and usable. If these simulations are done accurately, the instrument can be deployed, leading to more accurate weather forecasts and climate research. This demonstration system validates the simulations, specifically the realism of remotely sensed observations. The digital twin system is a low-cost way to improve instrument design used in meteorological and climatological research. The primary goal is to show how atmospheric data can improve the development and validation of new observational systems for meteorology and climate science. We have developed an interactive variability study system that uses a dynamic platform to visualize, assess, and grasp complex atmospheric dynamics. The dashboard is built using Python for backend operations and integrates tools such as the Streamlit framework for quick web application development and the Folium library for advanced geospatial visualizations. This dashboard acts as a bridge between advanced atmospheric modeling and spatio-temporal digital twin applications, showcasing the substantial benefits of integrating comprehensive model outputs into the simulation of observational systems.
Soil Methane and Carbon Dioxide Fluxes from Cropland and Riparian Buffers in Different Hydrogeomorphic Settings
(Wiley, 2015-07-01) Jacinthe, P. A.; Vidon, P.; Fisher, K.; Liu, X.; Baker, Matthew
Riparian buffers contribute to the mitigation of nutrient pollution in agricultural landscapes, but there is concern regarding their potential to be hot spots of greenhouse gas production. This study compared soil CO₂ and CH₄ fluxes in adjacent crop fields and riparian buffers (a flood-prone forest and a flood-protected grassland along an incised channel) and examined the impact of water table depth (WTD) and flood events on the variability of gas fluxes in riparian zones. Results showed significantly (P < 0.001) higher CO₂ emission in riparian areas than in adjoining croplands (6.8 ± 0.6 vs. 3.6 ± 0.5 Mg CO₂–C ha⁻¹ yr⁻¹; mean ± SE). Daily flux of CO₂ and soil temperature were significantly related (P < 0.002), with Q₁₀ values ranging between 1.75 and 2.53. Significant relationships (P < 0.05) were found between CH₄ daily flux and WTD. Flood events resulted in enhanced CH₄ emission (up to +44.5 mg CH₄–C m⁻² d⁻¹ in a swale) under warm soil conditions (>22°C), but the effect of flooding was less pronounced in early spring (emission <1.06 mg CH₄–C m⁻² d⁻¹), probably due to low soil temperature. Although CH₄ flux direction alternated at all sites, overall the croplands and the flood-affected riparian forest were CH₄ sources, with annual emission averaging +0.04 ± 0.17 and +0.92 ± 1.6 kg CH₄–C ha⁻¹, respectively. In the riparian forest, a topographic depression (<8% of the total area) accounted for 78% of the annual CH₄ emission, underscoring the significance of landscape heterogeneity on CH₄ dynamics in riparian buffers. The nonflooded riparian grassland, however, was a net CH₄ sink (−1.08 ± 0.22 kg CH₄–C ha⁻¹ yr⁻¹), probably due to the presence of subsurface tile drains and a dredged/incised channel at that study site. Although these hydrological alterations may have contributed to improvement in the CH₄ sink strength of the riparian grassland, this must be weighed against the water quality maintenance functions and other ecological services provided by riparian buffers.
Colonialism’s legacy has left Caribbean nations much more vulnerable to hurricanes
(The Conversation, 2024-10-22) Nibbs, Farah
The islands’ vulnerability has roots deep in the exploitative systems forced on them by colonialism, from slave-based land policies to ill-suited development that put lives in harm’s way.
Immigrant Status and Social Ties: An Intersectional Analysis of Older Adults in the United States
(Springer Nature, 2024-11-21) Nayak, Sameera Shukanta; Mair, Christine A.; Adewuyi, Suliyat O.
Diverse social ties are critical facilitators of well-being among older adults. Social ties might be especially important for aging immigrants who face multiple social and economic vulnerabilities over the life course. We investigated social ties (e.g., partners, children, other family, and friends) by immigrant status among older adults in the United States (U.S.). Data come from the 2018 Health and Retirement Study (N?=?4,006), a national sample of older adults in the U.S. We used multivariable logistic regression to compare social ties (e.g., partners, children, other family, and friends) by immigrant status. We further explored interactions with sex and race/ethnicity. Older immigrants are more likely to report that they can rely a lot on their partners (aOR?=?1.84, 95% CI 1.27, 2.68) but less likely to rely on friends (aOR?=?0.72, 95% CI, 0.55, 0.94) compared to non-immigrants. Older immigrants are also less likely to meet frequently with friends (aOR?=?0.66, 95% CI, 0.51, 0.86) and with other family (aOR?=?0.71, 95%, CI, 0.55, 0.91) compared to non-immigrants. Lastly, older immigrant men are significantly less likely to meet with friends compared to non-immigrant men (aOR?=?0.48, 95% CI, 0.32, 0.73). As the older population in the U.S. continues to diversify and immigrant older adults navigate their support options, older immigrants–especially men–may be at risk for less variation in their social support options, particularly from extended family members and friends.
Improved characterization of Dome Concordia for tracking calibration changes in MODIS reflective solar bands
(SPIE, 2024-11-20) McBride, Brent; Twedt, Kevin; Wu, Aisheng; Geng, Xu; Xiong, Xiaoxiong
Dome Concordia (Dome C) in Antarctica is an excellent calibration site for polar-orbiting Earth observation instruments due to its spectral, spatial, and temporal uniformity. These instruments also observe Dome C multiple times a day and at a variety of geometries. The MODIS Characterization Support Team uses regular observations of Dome C by Aqua and Terra MODIS to help validate and improve the calibration of the detector gain and response versus scan angle of the reflective solar bands used to generate NASA’s Level 1B reflectance products. The reflectance trends at Dome C are typically assessed on a yearly basis, due to a six-month sunlit observation period. In this work, we increase the temporal resolution of the trends from yearly to bi-monthly and reduce measurement noise using a reflectance-based snow BRDF model. We show results for Terra and Aqua MODIS BRDF-normalized reflectance using the Collection 7 calibration for bands 1-4, 8-9, and 17. The BRDF model significantly reduces the variations in the bi-monthly reflectance trends with the best results observed near nadir and for the blue bands 3, 8, and 9. The higher temporal sampling allows for better real-time identification of any calibration errors during the sunlit season. In addition, due to its polar location, Dome C is largely insensitive to the recent orbit drift of the Terra and Aqua satellites which has created challenges for MODIS calibration based on other on-board and Earth targets. Combined, these advantages will make Dome C a particularly important calibration reference target during the final years of the Terra and Aqua missions.
In-flight characterization of the Hyper-Angular Rainbow Polarimeter (HARP2) on the NASA PACE mission
(SPIE, 2024-11-20) McBride, Brent; Sienkiewicz, Noah; Xu, Xiaoguang; Puthukkudy, Anin; Fernandez-Borda, Roberto; Martins, J. Vanderlei
The Hyper-Angular Rainbow Polarimeter (HARP2) is a novel wide-field of view imaging polarimeter instrument on the recently-launched NASA Plankton Aerosol Cloud ocean Ecosystem (PACE) mission. Since launch on February 8 2024, HARP2 has taken over 6 months of global Earth data. In order for this data to meet scientific quality standards, we must ensure that it is as accurate as possible and over long periods of time. We use well-characterized Earth targets, such as Saharan deserts, as well as regular views of the Sun and dark frames to trend our on-orbit calibration. In this work, we discuss the preliminary performance trends derived from these activities and how well they compare with the HARP2 prelaunch calibration.
First results and on-orbit performance of the Hyper-Angular Rainbow Polarimeter (HARP2) on the PACE satellite
(SPIE, 2024-11-20) Martins, J. Vanderlei; Fernandez-Borda, Roberto; Puthukkudy, Anin; Xu, Xiaoguang; Sienkiewicz, Noah; Smith, Rachel; McBride, Brent; Dubovik, Oleg; Remer, Lorraine
The Hyper-Angular Rainbow Polarimeter-2 (HARP2) was launched on board the Plankton, Aerosol, Cloud and ocean Ecosystem (PACE) mission, in February 2024, for the global measurement of aerosol and cloud properties as well as to provide atmospheric correction over the footprint of the Ocean Color Instrument (OCI). HARP2 is designed to collect data over a wide field of view in the cross-track direction (+/-47deg) allowing for global coverage in about two days, as well as an even wider field of view in the along-track direction (+/-54deg) providing measurements over a wide range of scattering angles. HARP2 samples 10 angles at 440, 550, and 870nm focusing on aerosol and surface retrievals, and up to 60 angles at 670nm for the hyper-angular retrieval of cloud microphysical properties. The HARP2 instrument collects three nearly identical images with linear polarizers aligned at 0°, 45°, and 90° that can be converted to push-broom images of the I, Q, and U Stokes parameters for each angle, and each wavelength. The HARP2 technology was first demonstrated with the HARP CubeSat satellite which collected a limited dataset for 2 years from 2020 to 2022. HARP2 extends these measurements to a full global coverage in two days, seven days a week.
OreSat 0.5: next-generation small satellite for global cirrus cloud detection and mapping
(SPIE, 2024-11-20) McBride, Brent; Smith, Rachel E.; Greenberg, Andrew; Dixon, Scott; Muller, Jan-Peter; Martins, J. Vanderlei
The OreSat 0.5 is a novel small satellite developed in collaboration between Portland State University in Portland, Oregon, USA, the University of Maryland, Baltimore County, in Baltimore, MD, USA, and the Mullard Space Science Laboratory at University College London, Surrey, UK. OreSat 0.5 will demonstrate global cirrus cloud detection and mapping from a compact, low-cost platform. In this work, we preview the OreSat 0.5 mission and demonstrate the calibration and science behind its primary payload, the Cirrus Flux Camera (CFC). The CFC is a three-channel shortwave infrared radiometer (870, 1390, 1590 nm bands). Flux ratios between its three bands will be used to differentiate ice versus water and noncloud signals. Along-track and Across-track pointing up to ±45° will allow retrievals of heights and winds of the cirrus cloud tops. We discuss a preliminary pre-launch calibration of CFC and plans to expand upon and maintain this calibration vicariously on-orbit and through proxy sources. OreSat 0.5 launched to space on August 16 2024 and first light data is expected by Q4 2024.
Analysis of the Influence of Clear-Sky Fluxes on the Cloud-Type Mean Cloud Radiative Effects in the Tropical Convectively Active Regions With CERES Satellite Data
(AGU, 2024-11-20) Xu, Kuan-Man; Sun, Moguo; Zhou, Yaping
Cloud radiative effects (CREs) and cloud-type mean CREs depend upon how clear-sky fluxes are computed over a large area: those of the immediate environment of clouds or the regional mean clear-sky fluxes. Five convectively active regions in the Tropics, two over land (Africa and Amazon) and three over ocean (eastern and western Pacific and Atlantic), are selected to understand the influence of immediate environment of clouds on CREs. Fluxes derived from 19 years of high-resolution CERES satellite data, categorized by cloud type, are utilized. The cloud types are classified based on the joint cloud top pressure and cloud optical depth distribution. For the entire tropical region, differences in cloud-type mean CRE with regional mean and immediate environment clear skies range from −7.8 to 10.7 Wm⁻² for shortwave (SW), 2.9 to 15.8 Wm⁻² for longwave (LW), and 6.1 to 17.9 Wm⁻² for net, respectively. The oceanic and Amazonia regions have negative (positive) SW (LW) CRE differences, typically 2–6 Wm⁻² in SW but 7–10 Wm⁻² in LW, whereas Africa has positive SW and LW CRE differences (typically 20–30 Wm⁻², up to 40–50 Wm⁻²). The influence of immediate environment reduces the regionally averaged, that is, cloud-type mean CREs weighted by cloud fractions, SW cloud cooling, and LW cloud warming in four of the five regions except for Africa. For Africa, it increases the SW cloud cooling and greatly reduces the LW cloud warming, resulting in net cloud cooling as in other regions instead of warming. The implications of these findings for observational and modeling studies are discussed.
Tomographic reconstruction algorithms for retrieving two-dimensional ice cloud microphysical parameters using along-track (sub)millimeter-wave radiometer observations
(EGU, 2024-11-20) Liu, Yuli; Adams, Ian S.
The submillimeter-wave radiometer operating in the along-track scanning mode continuously collects brightness temperature (TB) data over a two-dimensional (2D) cloud cross-section as the platform moves forward. TB observations from multiple positions and viewing angles show great promise in better constraining the 2D cloud microphysical properties compared to single-angle observations. In this study, we develop two types of tomographic reconstruction algorithms to retrieve 2D ice water content (IWC) profiles using multi-angle TB observations. The one-dimensional (1D) tomographic algorithm performs 1D retrievals beam by beam using each TB observation at a specific position and angle to derive cloud properties along the propagation path. It then integrates the 1D retrieval results to construct 2D cloud distributions. The 2D tomographic algorithm directly constrains the 2D cloud microphysical properties using multi-angle scanning TB observations. Starting with an initial assumption, the algorithm iteratively refines the 2D cloud microphysical quantities by minimizing discrepancies between TB simulations and observations under prior constraints. Both tomographic algorithms are developed based on a hybrid of Bayesian Monte Carlo Integration (MCI) and Optimal Estimation Method (OEM). A simulation experiment is conducted to evaluate the performance of two tomographic reconstruction algorithms. The experiment demonstrates stable convergence of both tomographic methods, with the 2D tomographic algorithm exhibiting superior performance. The experiment results highlight the significant advantage of using multi-angle observations to constrain 2D cloud structure. Compared to nadir-only retrievals, the tomographic technique provides a detailed reconstruction of ice clouds’ inner structure with high spatial resolution. Also, the technique significantly improves retrieval accuracy by correcting systematic biases and reducing the derivation of retrieval errors. Furthermore, the tomography technique effectively increases detection sensitivity for small ice cloud particles.
Understanding Titan’s Prebiotic Chemistry: Synthesizing Amino Acids Through Aminonitrile Alkaline Hydrolysis
(ACS, 2024-11-20) Farnsworth, Kendra; McLain, Hannah L.; Chung, Angela; Trainer, Melissa G.
Titan is an ocean world with a plethora of organic material in its atmosphere and on its surface, making it an intriguing location in the search for habitable environments beyond Earth. Settled aerosols will mix with transient surface melts following cryovolcanic eruptions and impact events, driving hydrolysis reactions and prebiotic chemistry. Previous studies have shown that the hydrolysis of laboratory-synthesized Titan organics leads to the production of amino acids and other prebiotic molecules. The exact molecular structure of Titan aerosols remains unclear, yet aminonitriles have been hypothesized to be among the organic components. This laboratory study tested three reaction pathways that could potentially lead to the formation of amino acids: aminoacetonitrile → glycine, 2-aminopropanenitrile → alanine, and 4-aminobutanenitrile → γ-aminobutyric acid. Liquid chromatography mass spectrometry (LCMS) is used to quantify the abundance of amino acids over a 6-month period. We conclude that ammonia plays a key role in the synthesis of amino acids from aminonitriles, while the inclusion of salts (1 wt %) and minerals (25 mg/mL) did not have a significant effect on amino acid formation compared to ammonia. Rate constants (k) for alkaline hydrolysis of the aminonitriles were calculated. Our results suggest that if Titan’s surface melts have a composition, including at least 5% ammonia in water, and if aminonitriles are present in Titan’s organic aerosols, then amino acids will likely form. These results are highly relevant to the Dragonfly mission to Titan, which will sample impact melt material at Selk crater to search for prebiotic molecules.
Tree plantations and forest regrowth are linked to poverty reduction in Africa
(Nature, 2024-11-20) den Braber, Bowy; Hall, Charlotte M.; Rhemtulla, Jeanine M.; Fagan, Matthew E.; Rasmusssen, Laura Vang
Numerous countries have adopted large-scale tree planting programs as a climate mitigation strategy and to improve local livelihoods. However, it remains poorly documented how the surge in tree plantations has altered local livelihoods. Here, we assess whether tropical tree plantation expansion and forest regrowth across 18 African countries are associated with local people’s living standards. By combining a recent map that distinguishes tree plantations from regrowth from 2000 to 2012 with multidimensional poverty measures from more than 200,000 households, we find a positive association between people's living standards and areas where tree plantations have expanded or, to a lesser extent, forest regrowth has occurred. Because tree plantations make up a large proportion of recent increases in tropical tree cover – and controversy remains about their potential impacts on both biodiversity and local people – our study provides broad empirical support for the idea that tree plantations and forest regrowth can be linked with reduced poverty in the short term.
Ecological resistance in urban streams: the role of natural and legacy attributes
(University of Chicago Press, 2016-03) Utz, Ryan M.; Hopkins, Kristina G.; Beesley, Leah; Booth, Derek B.; Hawley, Robert J.; Baker, Matthew; Freeman, Mary C.; L. Jones, Krista
Urbanization substantially changes the physicochemical and biological characteristics of streams. The trajectory of negative effect is broadly similar around the world, but the nature and magnitude of ecological responses to urban growth differ among locations. Some heterogeneity in response arises from differences in the level of urban development and attributes of urban water management. However, the heterogeneity also may arise from variation in hydrologic, biological, and physicochemical templates that shaped stream ecosystems before urban development. We present a framework to develop hypotheses that predict how natural watershed and channel attributes in the pre-urban-development state may confer ecological resistance to urbanization. We present 6 testable hypotheses that explore the expression of such attributes under our framework: 1) greater water storage capacity mitigates hydrologic regime shifts, 2) coarse substrates and a balance between erosive forces and sediment supply buffer morphological changes, 3) naturally high ionic concentrations and pH pre-adapt biota to water-quality stress, 4) metapopulation connectivity results in retention of species richness, 5) high functional redundancy buffers trophic function from species loss, and 6) landuse history mutes or reverses the expected trajectory of eutrophication. Data from past comparative analyses support these hypotheses, but rigorous testing will require targeted investigations that account for confounding or interacting factors, such as diversity in urban infrastructure attributes. Improved understanding of the susceptibility or resistance of stream ecosystems could substantially strengthen conservation, management, and monitoring efforts in urban streams. We hope that these preliminary, conceptual hypotheses will encourage others to explore these ideas further and generate additional explanations for the heterogeneity observed in urban streams.
Optimizing Daily Fantasy Baseball Lineups: A Linear Programming Approach for Enhanced Accuracy
(2024-11-17) Grody, Max; Bansal, Sandeep; Ashqar, Huthaifa
Daily fantasy baseball has shortened the life cycle of an entire fantasy season into a single day. As of today, it has become familiar with more than 10 million people around the world who participate in online fantasy. As daily fantasy continues to grow, the importance of selecting a winning lineup becomes more valuable. The purpose of this paper is to determine how accurate FanDuel current daily fantasy strategy of optimizing daily lineups are and utilize python and linear programming to build a lineup optimizer for daily fantasy sports with the goal of proposing a more accurate model to assist daily fantasy participants select a winning lineup.

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