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Carrying Silences Across Borders: Tarun Kumar Speaks with Abdul Aijaz and Richa Nagar | चुप्पियाँ और सरहदें: तरुण कुमार के साथ अब्दुल ऐजाज़ और ऋचा नागर की बातचीत
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How New Communication Behaviors Evolve: Androgens as Modifiers of Neuromotor Structure and Function in Foot-Flagging Frogs
No full textHow diverse animal communication signals have arisen is a question that has fascinated many. Xenopus frogs have been a model system used for three decades to reveal insights into the neuroendocrine mechanisms and evolution of vocal diversity. Due to the ease of studying central nervous system control of the laryngeal muscles in vitro, Xenopus has helped us understand how variation in vocal communication signals between sexes and between species is produced at the molecular, cellular, and systems levels. Yet, it is becoming easier to make similar advances in non-model organisms. In this paper, we summarize our research on a group of frog species that have evolved a novel hind limb signal known as ‘foot flagging.’ We have previously shown that foot flagging is androgen dependent and that the evolution of foot flagging in multiple unrelated species is accompanied by the evolution of higher androgen hormone sensitivity in the leg muscles. Here, we present new preliminary data that compare patterns of androgen receptor expression and neuronal cell density in the lumbar spinal cord – the neuromotor system that controls the hind limb – between foot-flagging and non-foot-flagging frog species. We then relate our work to prior findings in Xenopus, highlighting which patterns of hormone sensitivity and neuroanatomical structure are shared between the neuromotor systems underlying Xenopus vocalizations and foot-flagging frogs\u27 limb movement and which appear to be species-specific. Overall, we aim to illustrate the power of drawing inspiration from experiments in model organisms, in which the mechanistic details have been worked out, and then applying these ideas to a non-model species to reveal new details, further complexities, and fresh hypotheses
The Less Visible Side of Transhumanism Is Dangerously Un-Radical
Full text linkAccording to transhumanists who urge the radical enhancement of human beings, humanity’s top priority should be engineering “posthumans,” whose features would include agelessness. Increasingly, transhumanism is critiqued on foundational grounds rather than based largely on anticipated results of its implementation, such as rising social inequality. This expansion is crucial but insufficient because, despite its radical aim, transhumanism reflects beliefs and attitudes that are evident in the broader culture. With a focus on the yearning to eliminate aging, I consider four of these: a disproportionate reliance on science and technology to address major human challenges; the conceptualization of human beings in terms of binaries like “young-old”; a repudiation of vulnerability; and intensifying perfectionism. Illuminating these interlocked commitments both deepens an existing critique of transhumanism and draws our attention to deleterious cultural views that must be vigorously contested if our commitment to human flourishing is to be deep and unwavering
Sealy-Jefferson et al. Responds to Invited Commentary by Joseph et al. with “Toward naming who and what is accountable for racial inequities in adverse Black maternal mental health”
Full text linkPer- and Polyfluoroalkyl Substance Exposure Risks in US Carceral Facilities, 2022
Full text linkObjectives. To assess the US incarcerated population’s risk of exposure to per- and polyfluoroalkyl substances (PFASs). Methods. We assessed how many of the 6118 US carceral facilities were located in the same hydrologic unit code watershed boundaries as known or likely locations of PFAS contamination. We conducted geospatial analyses on data aggregated from Environmental Protection Agency databases and a PFAS site tracker in 2022 to model the hydrologically feasible known and presumptive PFAS contamination sites for nearly 2 million incarcerated people. Results. Findings indicate that 5% (∼310) of US carceral facilities have at least 1 known source of PFAS contamination in the same watershed boundary and that it is at a higher elevation than the facility; also 47% (∼2285) have at least 1 presumptive source. A minimum of 990 000 people are incarcerated in these facilities, including at least 12 800 juveniles. Exposure risks faced by incarcerated youths are disproportionately underassessed. Conclusions. The long-term impacts from potential exposures to PFAS are preventable and exacerbate health inequities among incarcerated populations. Widespread public attention to PFASs can be parlayed into broader environmental monitoring for imprisoned people
Bridging the Gap Between in vivo and in vitro Modeling for Tissue Engineering: Conjugating Azlactone Hydrogels with Adhesive Peptides Using Photo-Click Reactions
No full textInvestigating the Role of Meteorin in Early CNS Development of Zebrafish
No full textNeurogenesis and gliogenesis are critical processes for neurodevelopment. Radial glial cells (RGCs), an essential progenitor cell population in the central nervous system (CNS), give rise to both neurons and glia throughout embryogenesis in vertebrates. Meteorin (metrn) is a secreted protein, an orphan ligand and a neurotrophic factor. It has been shown to play a regulatory role in RGC differentiation in-vitro (with mice cell cultures). I hypothesize that metrn may act as a unique regulator for RGC development in vivo. To investigate this, I first established the spatiotemporal gene expression patterns of both metrn & its paralog meteorin-like (metrnL) during zebrafish embryogenesis. Using hybridization chain reaction (HCR) procedures, I found that metrn and metrnL are expressed in both complementary and overlapping patterns that include regions of the CNS with known progenitor cell domains. I also conducted a preliminary colocalization study by combining both HCR and immunocytochemistry that revealed that metrn and metrnL do colocalize with RGCs. To be able to track metrn expression in real-time in live zebrafish embryos, I attempted to create a transgenic reporter line. This was done using a plasmid created in the Tol2 Gateway Cloning system to tag the metrn promoter with a GFP reporter. Although these attempts produced some successful transgenesis, the alleles isolated do not show metrn expression patterns in the CNS. Last but not least, I investigated loss of function of metrn by carrying out morpholino knockdown studies and CRISPR promoter KO studies. The morpholinos targeted to disrupt the translation of metrn while the CRISPR targeted to disrupt the transcription of metrn. Our preliminary data on phenotypic characterization also revealed developmental defects in regions with established metrn and metrnL expression. This includes abnormal developmental phenotypes in the brain (hydrocephalus), somite formation (compaction), trunk formation (tail truncation) and pronephros (kidney cyst formation). Moreover, HCR analysis on these metrn morphants revealed that expression of metrnL is altered, suggesting that metrn and metrnL may be working in a feedback mechanism. We posit that understanding how metrn & metrnL regulate RGC development can provide new insight into regulators mediating progenitor cells in the CNS. This would not only have implications in how the brain is formed, but also how neurodevelopmental disorders (including congenital brain cancers) may arise
System Identification with Neural Networks in the Smith College Geothermal Project
No full textThis thesis is intended to be a mathematical and practical primer to the concepts behind deep learning. It overviews the necessity and fundamentals of data-driven methods, particularly generalization and types of learning. It offers an introduction to neural networks and their relevance to system identification problems, including the theory of universal approximation. The early perceptron model is explained and a proof of the Perceptron Learning Algorithm is offered. Basic architecture of activation and loss functions are reviewed, as well as the method of learning network parameters via (stochastic) gradient descent and backpropagation. Then, specific literature relevant to the project is reviewed, with a special focus on [10] whose algorithm was the inspiration for the one developed in this thesis. Finally, the network used is described. The training data and its preprocessing, the network’s hyperparameters, and results of learning are discussed, and avenues for future work are suggested
Can Miami Corals Beat the Heat? Insights into the Algal Symbiont Assemblages of Highly Resilient ‘Urban Corals’ in Southeast Florida
No full textAnthropogenic stress on coral reef ecosystems is especially apparent in southeast Florida where disease outbreaks, bleaching events, and coastal development have caused substantial die-offs of these invaluable ecosystems. However, resilient coral communities have been found living in highly developed and urbanized habitats throughout southeast Florida, such as the Port of Miami. The corals found here, characterized as ‘urban corals’, show remarkable persistence surviving on artificial substrates despite extreme variability in environmental conditions and impacts of urban development. To better understand mechanisms of resilience among these urban corals, quantitative polymerase chain reaction (qPCR) was used to profile the abundance of four coral-associated genera of Symbiodiniaceae (Symbiodinium, Breviolum, Cladicopium, and Durusdinium), a clade of photosynthetic and endosymbiotic dinoflagellates. Corals from five species of interest were sampled throughout southeast Florida: Orbicella faveolata, Montastraea cavernosa, Colpophyllia natans, Diploria labyrinthiformis, and Pseudodiploria spp. Through this analysis, urban corals were shown to host higher abundances of symbionts from the genus Durusdinium, a known thermally tolerant symbiont genus. Dominance of this thermally tolerant symbiont in urbanized habitats partly explains how urban corals are able to persist under extreme environmental variability. This study builds on seven years of environmental monitoring, in situ molecular characterization, and ex situ experimentation of urban corals in southeast Florida, ultimately, aiding in the identification of mechanisms that contribute to the persistence of urban corals despite unfavorable environmental conditions. Combined with ongoing assessments of genetic relatedness among urban and offshore reef populations, this data demonstrates the value that urban corals have for conservation and restoration initiatives in coastal communities