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1. Geometry, analysis, and morphogenesis: Problems and prospects

   https://doi.org/10.1090/bull/1765  

   Lewicka, Marta ; Mahadevan, L. ( July 2022 , Bulletin of the American Mathematical Society)

   The remarkable range of biological forms in and around us, such as the undulating shape of a leaf or flower in the garden, the coils in our gut, or the folds in our brain, raise a number of questions at the interface of biology, physics, and mathematics. How might these shapes be predicted, and how can they eventually be designed? We review our current understanding of this problem, which brings together analysis, geometry, and mechanics in the description of the morphogenesis of low-dimensional objects. Starting from the view that shape is the consequence of metric frustration in an ambient space, we examine the links between the classical Nash embedding problem and biological morphogenesis. Then, motivated by a range of experimental observations and numerical computations, we revisit known rigorous results on curvature-driven patterning of thin elastic films, especially the asymptotic behaviors of the solutions as the (scaled) thickness becomes vanishingly small and the local curvature can become large. Along the way, we discuss open problems that include those in mathematical modeling and analysis along with questions driven by the allure of being able to tame soft surfaces for applications in science and engineering.

    

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2. Blockchains and Databases: Opportunities and Challenges for the Permissioned and the Permissionless

   https://doi.org/10.1007/978-3-030-54832-2_1  

   Agrawal, D. ; El Abbadi, A. ; Amiri, M.J. ; Maiyya, S. ; Zakhary, V. ( August 2020 , Advances in Databases and Information Systems)

   Darmont, J ; Novikov, B. ; Wrembel, R. (Ed.)

   Bitcoin [12] is a successful and interesting example of a global scale peer-to-peer cryptocurrency that integrates many techniques and protocols from cryptography, distributed systems, and databases. The main underlying data structure is blockchain, a scalable fully replicated structure that is shared among all participants and guarantees a consistent view of all user transactions by all participants in the system. In a blockchain, nodes agree on their shared states across a large network of untrusted participants. Although originally devised for cryptocurrencies, recent systems exploit its many unique features such as transparency, provenance, fault tolerance, and authenticity to support a wide range of distributed applications. Bitcoin and other cryptocurrencies use permissionless blockchains. In a permissionless blockchain, the network is public, and anyone can participate without a specific identity. Many other distributed applications, such as supply chain management and healthcare, are deployed on permissioned blockchains consisting of a set of known, identified nodes that still might not fully trust each other. This paper illustrates some of the main challenges and opportunities from a database perspective in the many novel and interesting application domains of blockchains. These opportunities are illustrated using various examples from recent research in both permissionless and permissioned blockchains. Two main themes unite the various examples: (1) the important role of distribution and consensus in managing large scale systems and (2) the need to tolerate malicious failures. The advent of cloud computing and large data centers shifted large scale data management infrastructures from centralized databases to distributed systems. One of the main challenges in designing distributed systems is the need for fault-tolerance. Cloud-based systems typically assume trusted infrastructures, since data centers are owned by the enterprises managing the data, and hence the design typically only assumes and tolerates crash failures. The advent of blockchain and the underlying premise that copies of the blockchain are distributed among untrusted entities has shifted the focus of fault-tolerance from tolerating crash failures to tolerating malicious failures. These interesting and challenging settings pose great opportunities for database researchers. 

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3. Effects of ROS pathway inhibitors and NADH and FADH2 linked substrates on mitochondrial bioenergetics and ROS emission in the heart and kidney cortex and outer medulla

   https://doi.org/10.1016/j.abb.2023.109690  

   Sadri, Shima ; Tomar, Namrata ; Yang, Chun ; Audi, Said H ; Cowley, Allen W ; Dash, Ranjan K ( August 2023 , Archives of Biochemistry and Biophysics)

   Mitochondria are major sources of reactive oxygen species (ROS), which play important roles in both physiological and pathological processes. However, the specific contributions of different ROS production and scavenging components in the mitochondria of metabolically active tissues such as heart and kidney cortex and outer medulla (OM) are not well understood. Therefore, the goal of this study was to determine contributions of different ROS production and scavenging components and provide detailed comparisons of mitochondrial respiration, bioenergetics, ROS emission between the heart and kidney cortex and OM using tissues obtained from the same Sprague-Dawley rat under identical conditions and perturbations. Specifically, data were obtained using both NADH-linked substrate pyruvate + malate and FADH2-linked substrate succinate followed by additions of inhibitors of different components of the electron transport chain (ETC) and oxidative phosphorylation (OxPhos) and other ROS production and scavenging systems. Currently, there is limited data available for the mitochondria of kidney cortex and OM, the two major energy-consuming tissues in the body only next to the heart, and scarce quantitative information on the interplay between mitochondrial ROS production and scavenging systems in the three tissues. The findings from this study demonstrate significant differences in mitochondrial respiratory and bioenergetic functions and ROS emission among the three tissues. The results quantify the rates of ROS production from different complexes of the ETC, identify the complexes responsible for variations in mitochondrial membrane depolarization and regulations of ROS production, and quantify the contributions of ROS scavenging enzymes towards overall mitochondrial ROS emission. These findings advance our fundamental knowledge of tissue-specific and substrate-dependent mitochondrial respiratory and bioenergetic functions and ROS emission. This is important given the critical role that excess ROS production, oxidative stress, and mitochondrial dysfunction in the heart and kidney cortex and OM play in the pathogenesis of cardiovascular and renal diseases, including salt-sensitive hypertension. Keywords: Forward and reverse electron transfer; Mitochondrial metabolism; NADPH oxidase; Oxidative stress; ROS emission; ROS production and scavenging; Respiration and bioenergetics. 

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4. Public concerns and connected and automated vehicles: safety, privacy, and data security

   https://doi.org/10.1057/s41599-022-01110-x  

   Lee, Dasom ; Hess, David J. ( December 2022 , Humanities and Social Sciences Communications)

   One dimension of the emerging politics of connected and automated vehicles (CAVs) is the development of public concerns over their societal implications and associated policy issues. This study uses original survey data from the United States to contribute to the anticipation of future policy and political issues for CAVs. Several studies have surveyed the public regarding CAVs; however, there are few studies that highlight the multidimensional public concerns that CAVs will most likely bring. The study breaks down the concept of “public” by showing that the demographic variables of gender, age, race, ethnicity, income, location (rural, suburban, urban), and political ideology (conservative, moderate, liberal) are significantly associated with three of the most salient public concerns to date (safety, privacy, and data security). Furthermore, the effects of demographic variables also vary across the type of policy issue. For example, women tend to be more concerned about safety than their male counterparts, and Hispanics (Latinx) tend to be more concerned about privacy than non-Hispanics. The research shows how the social scientific analysis of the “politics” of CAVs will require attention to the variegated connections between different types of public concern and different demographic variables.

    

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5. Ohm’s law lost and regained: observation and impact of zeros and poles

   Joshi, Krishna ; Kurtz, Israel ; Shi, Zhou ; Genack, A Z ( June 2024 , Los Alamos Arxiv)

   The quantum conductance and its classical wave analogue, the transmittance, are given by the sum of the eigenvalues of the transmission matrix. The lowest transmission eigenvalue in diffusive media might be expected to play a negligible role in the conductance, and, in any case, to be too small to be observed. Here, we observe the lowest transmission eigenchannel in microwave waveguides, though it is orders of magnitude below the nominal noise level, and show that the transmittance is pulled down by global correlation among transmission eigenvalues and among zeros and poles of the transmission matrix. Transmission vanishes either when the energy density on the sample output vanishes at topological transmission zeros or when the longitudinal velocity vanishes precisely at the crossover to a new channel. This lowers the conductance by an amount proportional to the modulation of the density of states. In accord with the correspondence principle, the conductance approaches Ohm’s law as the number of channels increases with sample width. The exploration of the transmission matrix opens the door to a new understanding of mesoscopic transport and ultrasensitive detection techniques. 

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