All Faculty Deposits
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The "All Faculty Deposits" collection contains works deposited by faculty and appointed delegates from the Elements (EFARs) system. For help with Elements, see Frequently Asked Questions on the Provost's website. In general, items can only be deposited if the item is a scholarly article that is covered by Virginia Tech's open access policy, or the item is openly licensed or in the public domain, or the item is permitted to be posted online under the journal/publisher policy, or the depositor owns the copyright. See Right to Deposit on the VTechWorks Help page. If you have questions email us at vtechworks@vt.edu.
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Browsing All Faculty Deposits by Content Type "Article - Refereed"
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- The 2020 Indian Farm Laws in the Global Financial-Agritech Accumulation RegimeGill, Bikrum Singh (2021-10-31)Much of the popular analysis of the 2020 farmers protests in India identifies an “authoritarian” BJP government as the primary antagonistic force threatening the livelihoods of farmers in major grain producing states such as Punjab. This paper is motivated by concern that such a “methodologically nationalist” and “presentist” account risks obscuring more than it reveals regarding what is at stake in the contestations over the 2020 farm laws. It addresses these limitations by asking instead how the contestation over the farm laws renews the confrontation over the appropriation of the surplus value of the “agrarian South” that was set in motion by the rise of the neoliberal form of global capital accumulation in the late twentieth century. Locating the contemporary moment within the long history and broader geography of neoliberal capitalist imperialism brings to light the accumulation imperatives of global financial-agribusiness capital as key motive forces underpinning the farm laws. Attention is thus drawn in this paper to how the deepening of the privatization, liberalization, and financialization of agriculture in the Global South remains a key strategy for addressing global capital’s structural crises of over-production and over-accumulation. The paper argues that the intensification of neoliberal agrarian restructuring in India via the 2020 farm laws has opened further space for both a familiar mode of global agribusiness accumulation that aims to capture the surplus value of the real agricultural economy and for an emergent agritech mode of accumulation that is centered more on harvesting data in order to generate profits through financial speculation in the derivative agricultural economy. The paper concludes by emphasizing that the farmers movement is correct in contesting the farm laws, as the deepening of Indian agriculture’s integration into global capitalism threatens to render farmers into a category of permanently surplus labor.
- 2D and 3D Chromosome Painting in Malaria MosquitoesGeorge, Phillip; Sharma, Atashi; Sharakhov, Igor V. (Journal of Visualized Experiments, 2014-01-01)Fluorescent in situ hybridization (FISH) of whole arm chromosome probes is a robust technique for mapping genomic regions of interest, detecting chromosomal rearrangements, and studying three-dimensional (3D) organization of chromosomes in the cell nucleus. The advent of laser capture microdissection (LCM) and whole genome amplification (WGA) allows obtaining large quantities of DNA from single cells. The increased sensitivity of WGA kits prompted us to develop chromosome paints and to use them for exploring chromosome organization and evolution in non-model organisms. Here, we present a simple method for isolating and amplifying the euchromatic segments of single polytene chromosome arms from ovarian nurse cells of the African malaria mosquito Anopheles gambiae. This procedure provides an efficient platform for obtaining chromosome paints, while reducing the overall risk of introducing foreign DNA to the sample. The use of WGA allows for several rounds of re-amplification, resulting in high quantities of DNA that can be utilized for multiple experiments, including 2D and 3D FISH. We demonstrated that the developed chromosome paints can be successfully used to establish the correspondence between euchromatic portions of polytene and mitotic chromosome arms in An. gambiae. Overall, the union of LCM and single-chromosome WGA provides an efficient tool for creating significant amounts of target DNA for future cytogenetic and genomic studies.
- 2D Hierarchical Microbarcodes with Expanded Storage Capacity for Optical Multiplex and Information EncryptionWorch, Josh; Xie, Yujie; Tong, Zaizai; Rho, Julia; Dove, Andrew; O'Reilly, Rachel (2023-11-28)The design of nanosegregated fluorescent tags/barcodes by geometrical patterning with precise dimensions and hierarchies could integrate multilevel optical information within one carrier and enhance microsized barcoding techniques for ultrahigh-density optical data storage and encryption. However, precise control of the spatial distribution in micro/nanosized matrices intrinsically limits the accessible barcoding applications in terms of material design and construction. Here, crystallization forces are leveraged to enable a rapid, programmable molecular packing and rapid epitaxial growth of fluorescent units in 2D via crystallization-driven self-assembly. The fluorescence encoding density, scalability, information storage capacity, and decoding techniques of the robust 2D polymeric barcoding platform are explored systematically. These results provide both a theoretical and an experimental foundation for expanding the fluorescence storage capacity, which is a longstanding challenge in state-of-the-art microbarcoding techniques and establish a generalized and adaptable coding platform for high-throughput analysis and optical multiplexing.
- (2S,4R)-4-Fluoro-pyrrolidinium-2-carboxyl-ate.Hobart, David B. Jr.; Merola, Joseph S. (International Union of Crystallography, 2012-08-01)The crystal structure of the title compound, C(5)H(8)FNO(2), at 100 K, displays inter-molecular N-H⋯O hydrogen bonding between the ammonium and carboxyl-ate groups as a result of its zwitterionic nature in the solid state. The five-membered ring adopts an envelope conformation with the C atom at the 3-position as the flap. The compound is of inter-est with respect to the synthesis and structural properties of synthetic collagens. The absolute structure was determined by comparison with the commercially available material.
- 3,4-Dihydroxyphenylacetaldehyde synthase and cuticle formation in insectsLiao, Chenghong; Liang, Jing; Han, Qian; Li, Jianyong (2018-06-02)Cuticle is the most important structure that protects mosquitoes and other insect species from adverse environmental conditions and infections of microorganism. The physiology and biochemistry of insect cuticle formation have been studied for many years and our understanding of cuticle formation and hardening has increased considerably. This is especially true for flexible cuticle. The recent discovery of a novel enzyme that catalyzes the production of 3,4-dihydroxyphenylacetaldehyde (DOPAL) in insects provides intriguing insights concerning the flexible cuticle formation in insects. For convenience, the enzyme that catalyzes the production DOPAL from L-dopa is named DOPAL synthase. In this mini-review, we summarize the biochemical pathways of cuticle formation and hardening in general and discuss DOPAL synthase-mediated protein crosslinking in insect flexible cuticle in particular.
- A 3-D Finite-Element Minipig Model to Assess Brain Biomechanical Responses to Blast ExposureSundaramurthy, Aravind; Kote, Vivek Bhaskar; Pearson, Noah; Boiczyk, Gregory M.; McNeil, Elizabeth M.; Nelson, Allison J.; Subramaniam, Dhananjay Radhakrishnan; Rubio, Jose E.; Monson, Kenneth; Hardy, Warren N.; VandeVord, Pamela J.; Unnikrishnan, Ginu; Reifman, Jaques (Frontiers, 2021-12-17)Despite years of research, it is still unknown whether the interaction of explosion-induced blast waves with the head causes injury to the human brain. One way to fill this gap is to use animal models to establish “scaling laws” that project observed brain injuries in animals to humans. This requires laboratory experiments and high-fidelity mathematical models of the animal head to establish correlates between experimentally observed blast-induced brain injuries and model-predicted biomechanical responses. To this end, we performed laboratory experiments on Göttingen minipigs to develop and validate a three-dimensional (3-D) high-fidelity finite-element (FE) model of the minipig head. First, we performed laboratory experiments on Göttingen minipigs to obtain the geometry of the cerebral vasculature network and to characterize brain-tissue and vasculature material properties in response to high strain rates typical of blast exposures. Next, we used the detailed cerebral vasculature information and species-specific brain tissue and vasculature material properties to develop the 3-D high-fidelity FE model of the minipig head. Then, to validate the model predictions, we performed laboratory shock-tube experiments, where we exposed Göttingen minipigs to a blast overpressure of 210 kPa in a laboratory shock tube and compared brain pressures at two locations. We observed a good agreement between the model-predicted pressures and the experimental measurements, with differences in maximum pressure of less than 6%. Finally, to evaluate the influence of the cerebral vascular network on the biomechanical predictions, we performed simulations where we compared results of FE models with and without the vasculature. As expected, incorporation of the vasculature decreased brain strain but did not affect the predictions of brain pressure. However, we observed that inclusion of the cerebral vasculature in the model changed the strain distribution by as much as 100% in regions near the interface between the vasculature and the brain tissue, suggesting that the vasculature does not merely decrease the strain but causes drastic redistributions. This work will help establish correlates between observed brain injuries and predicted biomechanical responses in minipigs and facilitate the creation of scaling laws to infer potential injuries in the human brain due to exposure to blast waves.
- "33rd Balloon"Vollmer, Matthew (2016-07-22)
- 3D X-ray analysis of the subterranean burrowing depth and pupal chamber size of Laricobius (Coleoptera: Derodontidae), a specialist predator of Adelges tsugae (Hemiptera: Adelgidae)Hillen, Ashleigh P.; Foley, Jeremiah R.; Salcedo, Mary K.; Socha, John J.; Salom, Scott M. (Oxford University Press, 2023-05-01)The non-native hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), has caused a significant decline of eastern hemlock, Tsuga canadensis L. (Pinales: Pinaceae), and Carolina hemlock, Tsuga caroliniana Engelmann (Pinales: Pinaceae), in eastern North America. Biological control of HWA has focused on the use of 2 Laricobius spp. (Coleoptera: Derodontidae), natural predators of HWA, which require arboreal and subterranean life phases to complete their development. In its subterranean phase, Laricobius spp. are subject to abiotic factors including soil compaction or soil-applied insecticides used to protect hemlock from HWA. This study used 3D X-ray microcomputed tomography (micro-CT) to identify the depth at which Laricobius spp. burrows during its subterranean lifecycle, characterize pupal chamber volume, and determine whether soil compaction had a significant effect on these variables. The mean burrowing depth in the soil of individuals was 27.0 mm ± 14.8 (SD) and 11.4 mm ± 11.8 (SD) at compaction levels of 0.36 and 0.54 g/ cm3, respectively. The mean pupal chamber volume was 11.15 mm3 ± 2.8 (SD) and 7.65 mm3 ± 3.5 (SD) in soil compacted at 0.36 and 0.54 g/cm3, respectively. These data show that soil compaction influences burrowing depth and pupal chamber size for Laricobius spp.This information will help us better identify the effect of soil-applied insecticide residues on estivating Laricobius spp. and soil-applied insecticide residues in the field. Additionally, these results demonstrate the utility of 3D micro-CT in assessing subterranean insect activity in future studies.
- 5-year follow-up of adolescents with social anxiety disorder: Current functioning during COVID-19Carlton, Corinne N.; Garcia, Katelyn M.; Honaker, Makayla; Richey, John A.; Ollendick, Thomas H. (Elsevier, 2023-04)The present study followed-up adolescents with social anxiety disorder (SAD) during the COVID-19 pandemic, approximately 5-years following their participation in an Attention Bias Modification Training (ABMT) program (Ollendick et al., 2019). The current study aimed to evaluate current functioning and quality of life (QoL) during the emerging adulthood period. Participants included 27 young adults who completed a randomized controlled trial of ABMT and were available for follow-up. Participants filled out self-report measures of QoL and functioning and underwent a clinical interview to assess current severity of social anxiety. Clinician-rated symptoms of SAD significantly decreased from post-treatment to 5-year follow-up. Additionally, results demonstrated that social anxiety severity was significantly related to poorer self-reported physical and psychological health as well as poorer functioning with regard to social distancing fears during COVID-19. Lastly, when evaluating change in symptoms over time, increases in social anxiety severity over a 5-year period significantly predicted worsened social distancing fears during COVID-19.
- 7.0-T Magnetic Resonance Imaging Characterization of Acute Blood-Brain-Barrier Disruption Achieved with Intracranial Irreversible ElectroporationGarcia, Paulo A.; Rossmeisl, John H. Jr.; Robertson, John L.; Olson, JohnD.; Johnson, Annette J.; Ellis, Thomas L.; Davalos, Rafael V. (PLOS, 2012-11-30)The blood-brain-barrier (BBB) presents a significant obstacle to the delivery of systemically administered chemotherapeutics for the treatment of brain cancer. Irreversible electroporation (IRE) is an emerging technology that uses pulsed electric fields for the non-thermal ablation of tumors. We hypothesized that there is a minimal electric field at which BBB disruption occurs surrounding an IRE-induced zone of ablation and that this transient response can be measured using gadolinium (Gd) uptake as a surrogate marker for BBB disruption. The study was performed in a Good Laboratory Practices (GLP) compliant facility and had Institutional Animal Care and Use Committee (IACUC) approval. IRE ablations were performed in vivo in normal rat brain (n = 21) with 1-mm electrodes (0.45 mm diameter) separated by an edge-to-edge distance of 4 mm. We used an ECM830 pulse generator to deliver ninety 50-ms pulse treatments (0, 200, 400, 600, 800, and 1000 V/cm) at 1 Hz. The effects of applied electric fields and timing of Gd administration (25, +5, +15, and +30 min) was assessed by systematically characterizing IRE-induced regions of cell death and BBB disruption with 7.0-T magnetic resonance imaging (MRI) and histopathologic evaluations. Statistical analysis on the effect of applied electric field and Gd timing was conducted via Fit of Least Squares with a = 0.05 and linear regression analysis. The focal nature of IRE treatment was confirmed with 3D MRI reconstructions with linear correlations between volume of ablation and electric field. Our results also demonstrated that IRE is an ablation technique that kills brain tissue in a focal manner depicted by MRI (n = 16) and transiently disrupts the BBB adjacent to the ablated area in a voltage-dependent manner as seen with Evan’s Blue (n = 5) and Gd administration.
- The 750 GeV diphoton excess in unified SU(2)(L) x SU(2)(R) x SU(4) models from noncommutative geometryAydemir, U.; Minic, Djordje; Sun, C.; Takeuchi, Tatsu (World Scientific, 2016-06-14)
- A Time-lagged Examination of Voluntary and Task-related Green Behavior in the Travel IndustryDhir, Amandeep; Talwar, Shalini; Raj, Sahil; Sampat, Brinda; Nicolau, Juan Luis (Sage, 2024-02-09)With climate change continuing to threaten the earth’s ecosystems, the travel industry is under increased pressure to adopt green policies. The effective implementation of these policies is largely dependent on employee commitment, but research offering insights into employees’ green behavior in the travel industry is sparse. We addressed this gap using the value-belief-norm theory to conceptualize the drivers of employees’ task-related and voluntary green behaviors. We examined the impact of values (biospheric, altruistic, and egoistic), beliefs (the new environmental paradigm, awareness of consequences, and ascription of responsibility), and pro-environmental personal norms on these outcomes. Analyzing time-lagged data collected in three waves from 186 hotel employees, we found a positive sequential association of biospheric values with beliefs, norms, and green behaviors. From a theoretical viewpoint, our study grounds hotel employees’ green behaviors in a prosocial theory, thereby offering a relatively new yet pertinent explanation of these behaviors.
- Abdominal ultrasonographic findings at diagnosis of osteosarcoma in dogs and association with treatment outcomeSacornrattana, O.; Dervisis, Nikolaos G.; McNiel, E. A. (Wiley-Blackwell, 2013-09-01)The purpose of this study was to describe abdominal ultrasonographic findings present at diagnosis of osteosarcoma (OSA) in dogs and to investigate for associations with treatment outcome. Medical records from 118 dogs diagnosed with OSA that had abdominal ultrasonography performed as part of their initial evaluation were reviewed. Fifty-seven percent had ultrasonographic abnormalities identified. The organ with the highest frequency of ultrasonographic changes was the spleen. While most sonographic changes were considered to be either benign or of unknown clinical consequences, metastases were identified in three dogs (2.5%), two of which (1.7%) did not have other evidence of metastasis. Dogs with any ultrasonographic abnormality were less likely to receive definitive therapy (P = 0.005) and exhibited shorter survival, although the latter observation was not statistically significant (P = 0.071). However, the identification of lesions in either the liver (P = 0.021) or the kidney (P = 0.003) was statistically associated with shorter survival.
- Ablation of OCT4 function in cattle embryos by double electroporation of CRISPR-Cas for DNA and RNA targeting (CRISPR-DART)Nix, Jada L.; Schettini, Gustavo P.; Speckhart, Savannah L.; Ealy, Alan D.; Biase, Fernando H. (Oxford University Press, 2023-11-01)CRISPR-Cas ribonucleoproteins (RNPs) are important tools for gene editing in preimplantation embryos. However, the inefficient production of biallelic deletions in cattle zygotes has hindered mechanistic studies of gene function. In addition, the presence of maternal RNAs that support embryo development until embryonic genome activation may cause confounding phenotypes. Here, we aimed to improve the efficiency of biallelic deletions and deplete specific maternal RNAs in cattle zygotes using CRISPR-Cas editing technology. Two electroporation sessions with Cas9D10A RNPs targeting exon 1 and the promoter of OCT4 produced biallelic deletions in 91% of the embryos tested. In most cases, the deletions were longer than 1,000 nucleotides long. Electroporation of Cas13a RNPs prevents the production of the corresponding proteins. We electroporated Cas9D10A RNPs targeting exon 1, including the promoter region, of OCT4 in two sessions with inclusion of Cas13a RNPs targeting OCT4 mRNAs in the second session to ablate OCT4 function in cattle embryos. A lack of OCT4 resulted in embryos arresting development prior to blastocyst formation at a greater proportion (13%) than controls (31.6%, P < 0.001). The few embryos that developed past the morula stage did not form a normal inner cell mass. Transcriptome analysis of single blastocysts, confirmed to lack exon 1 and promoter region of OCT4, revealed a significant (False Discovery Rate, FDR < 0.1) reduction in transcript abundance of many genes functionally connected to stemness, including markers of pluripotency (CADHD1, DPPA4, GNL3, RRM2). The results confirm that OCT4 is a key regulator of genes that modulate pluripotency and is required to form a functional blastocyst in cattle.
- Abnormal Behavior Detection Based on Traffic Pattern Categorization in Mobile Cellular NetworksDe Almeida, J. M.; Pontes, C. F. T.; DaSilva, Luiz A.; Both, C. B.; Gondim, J. J. C.; Ralha, Celia G.; Marotta, M. A. (IEEE, 2021-01-01)Abnormal behavior in mobile cellular networks can cause network faults and consequent cell outages, a major reason for operational cost increase and revenue loss for operators. Nonetheless, network faults and cell outages can be avoided by monitoring abnormal situations in the network and acting accordingly. Thus, anomaly detection is an important component of self-healing control and network management. Network operators may use the detected abnormal behavior to quantify numerically their intensity. The quantification of abnormal behavior assists the characterization of potential regions for infrastructure updates and to support the creation of public policies for local connectivity enhancements. We propose an unsupervised learning solution for anomaly detection in mobile networks using Call Detail Records (CDR) data. We evaluate our solution using a real CDR data set provided by an Italian operator and compare it against other state-of-the-art solutions, showing a performance improvement of around 35%. We also demonstrate the relevance of considering the distinct traffic patterns of diverging geographic areas for anomaly detection in mobile networks, an aspect often ignored in the literature.
- Abundance and Speciation of Surface Oxygen on Nanosized Platinum Catalysts and Effect on Catalytic ActivitySerra-Maia, Rui; Winkler, Christopher; Murayama, Mitsuhiro; Tranhuu, Kevin; Michel, F. Marc (2018-06-18)Oxygen at the surface of nanosized platinum has a direct effect on catalytic activity of oxidation−reduction chemical reactions. However, the abundance and speciation of oxygen remain uncertain for platinum with different particle size and shape characteristics, which has hindered the development of fundamental property−activity relationships. We have characterized two commercially available platinum nanocatalysts known as Pt black and Pt nanopowder to evaluate the effects of synthesis and heating conditions on the physical and surface chemical properties, as well as on catalytic activity. Characterization using complementary electron microscopy, X-ray scattering, and spectroscopic methods showed that the larger average crystallite size of Pt nanopowder (23 nm) compared to Pt black (11 nm) corresponds with a 70% greater surface oxygen concentration. Heating the samples in air resulted in an increase in surface oxygen concentration for both nanocatalysts. Surface oxygen associated with platinum is in the form of chemisorbed oxygen, and no significant amounts of chemically bonded platinum oxide were found for any of the samples. The increase in surface oxygen abundance during heating depends on the initial size and surface oxygen content. Hydrogen peroxide decomposition rate measurements showed that larger particle size and higher surface chemisorbed oxygen correlate with enhanced catalytic activity. These results are particularly important for future studies that aim to relate the properties of platinum, or other metal nanocatalysts, with surface reactivity.
- Acanthomorphic acritarchs of the Doushantuo Formation from an upper slope section in northwestern Hunan Province, South China, with implications for early–middle Ediacaran biostratigraphyOuyang, Q.; Guan, C.; Zhou, C.; Xiao, S. (2017-09)
- Accelerating changes in ice mass within Greenland, and the ice sheet's sensitivity to atmospheric forcingBevis, M.; Harig, C.; Khan, S. A.; Brown, A.; Simons, F. J.; Willis, Michael J.; Fettweis, X.; Van Den Broeke, M. R.; Madsen, F. B.; Kendrick, E.; Caccamise, D. J.; Van Dam, T.; Knudsen, P.; Nylen, T. (Proceedings of the National Academy of Sciences, 2019-01-22)From early 2003 to mid-2013, the total mass of ice in Greenland declined at a progressively increasing rate. In mid-2013, an abrupt reversal occurred, and very little net ice loss occurred in the next 12-18 months. Gravity Recovery and Climate Experiment (GRACE) and global positioning system (GPS) observations reveal that the spatial patterns of the sustained acceleration and the abrupt deceleration in mass loss are similar. The strongest accelerations tracked the phase of the North Atlantic Oscillation (NAO). The negative phase of the NAO enhances summertime warming and insolation while reducing snowfall, especially in west Greenland, driving surface mass balance (SMB) more negative, as illustrated using the regional climate model MAR. The spatial pattern of accelerating mass changes reflects the geography of NAO-driven shifts in atmospheric forcing and the ice sheet's sensitivity to that forcing. We infer that southwest Greenland will become a major future contributor to sea level rise.
- Acceleration of tensor-product operations for high-order finite element methodsŚwirydowicz, K.; Chalmers, N.; Karakus, A.; Warburton, T. (2017-09)This paper is devoted to GPU kernel optimization and performance analysis of three tensor-product operators arising in finite element methods. We provide a mathematical background to these operations and implementation details. Achieving close-to-the-peak performance for these operators requires extensive optimization because of the operators' properties: low arithmetic intensity, tiered structure, and the need to store intermediate results inside the kernel. We give a guided overview of optimization strategies and we present a performance model that allows us to compare the efficacy of these optimizations against an empirically calibrated roofline.
- An accountability evaluation for the industry's responsible use of brand mascots and licensed media characters to market a healthy diet to American childrenKraak, Vivica; Story, M. (Wiley-Blackwell, 2015-06-01)