770 Projects, page 1 of 154
Inhalation of microscale particles can cause severe health issues in respiratory and cardiovascular systems of humans. Trapping airborne particles by water droplets is one of the most widely used methods to reduce the particle concentration in polluted air. However, generating intensive micro-droplets via spraying or ultrasonic atomization normally requires specialized equipment and a large amount of energy. In this project, I propose a novel and cost-effective approach to capture particles by utilizing abundant self-jumping droplets generated during condensation on a superhydrophobic surface. Since the condensation process is ubiquitous and can be found in various heat transfer devices such as air conditioners, the proposed strategy will significantly reduce the expenses and energy costs for particle removal. In particular, to enhance the particle trapping rate, I intend to explore the rational superhydrophobic surface topography that allows continuous jumping-droplet condensation. I will first analyze the condensing droplet wetting dynamics using the cutting-edge confocal microscopy developed by the host lab. The results obtained will help to optimize the surface structures to achieve the durable condensate repellency. Next, I will investigate the effects of jumping droplet characteristics on the particle-droplet interaction from a single-droplet perspective. Finally, I will use my expertise in thermal physics to quantitatively correlate global condensation heat transfer and particle trapping performance. By integrating these interdisciplinary studies, the project will make a conceptual breakthrough in mitigating air pollution without additional energy consumption, and pave the way for the next-generation climate control devices with built-in air purification capabilities.
A longstanding question in the design of programming languages is how to balance safety and control. C-like languages give programmers low-level control over resource management at the expense of safety, whereas Java-like languages give programmers safe high-level abstractions at the expense of control. Rust is a new language developed at Mozilla Research that marries together the low-level flexibility of modern C++ with a strong "ownership-based" type system guaranteeing type safety, memory safety, and data race freedom. As such, Rust has the potential to revolutionize systems programming, making it possible to build software systems that are safe by construction, without having to give up low-level control over performance. Unfortunately, none of Rust's safety claims have been formally investigated, and it is not at all clear that they hold. To rule out data races and other common programming errors, Rust's core type system prohibits the aliasing of mutable state, but this is too restrictive for implementing some low-level data structures. Consequently, Rust's standard libraries make widespread internal use of unsafe blocks, which enable them to opt out of the type system when necessary. The hope is that such unsafe code is properly encapsulated, so that Rust's language-level safety guarantees are preserved. But due to Rust's reliance on a weak memory model of concurrency, along with its bleeding-edge type system, verifying that Rust and its libraries are actually safe will require fundamental advances to the state of the art. In this project, we aim to equip Rust programmers with the first formal tools for verifying safe encapsulation of unsafe code. Any realistic languages targeting this domain in the future will encounter the same problem, so we expect our results to have lasting impact. To achieve this goal, we will build on recent breakthrough developments by the PI and collaborators in concurrent program logics and semantic models of type systems.
The goal of this research is to identify and characterize genetic, behavioural and biochemical mechanisms underlying reciprocal local adaptation between partners in a complex mutualism. It will focus on a unique and outstanding model system found in the New World tropics: the “devil’s gardens” created by the ant, Myrmelachista schumanni, whose workers systematically attack and kill seedlings of foreign plants that germinate too close to their host plants. This cultivation behaviour results in low diversity, orchard-like stands of their host plants in the middle of some of the most diverse rainforests on earth. This project will bring together researchers from Harvard University and the Max Planck Institute to address three main questions through a combination of newly developed genome sequencing techniques, large-scale field-ecology behavioural experiments and state-of-the-art chemical analyses: (1) Do Myrmelachista schumanni and its host plants reciprocally influence each other’s population sizes, level of gene flow and genetic structure? (2) How specialized are interactions between Myrmelachista schumanni and the several species of plants that it cultivates? (3) What are some of the proximate mechanisms underlying host specificity, and in particular, can ants recognize different plant species and if so, how? In carrying out this research, postdoctoral fellow Pierre-Jean Malé will expand his expertise by gaining training in phylogenomics and chemical ecology. The project, referred to here as "RELOAD" (forREciprocal LOcal ADaptations), will also enable him to broaden the ecological and evolutionary scale of his research, and enhance his long-term goal of obtaining a faculty position at a European university and/or research institution.
Advancing age is the major risk factor for many serious illnesses, including cancer, cardiovascular disease, and dementia. The rising number of older individuals is thus causing a major burden of ill health. However, individuals that reach an exceptional old age often seem to escape or delay age-related diseases, and part of this trait seems to be encoded in their genome. Hence, by studying the genome of long-lived individuals, we may be able to identify mechanisms that could be targeted for healthy ageing in the general population. My previous work suggests that large genome-wide association studies (GWAS) of long-lived individuals can be used to identify genetic variants involved in longevity. However, the common genetic variants thus far identified using GWAS only explain a minor part of the genetic component of longevity. This trait, therefore, may well be mainly determined by rare genetic variants, which can be detected using whole-genome or exome sequencing of long-lived families or exceptionally long-lived individuals. The aim of the proposed project is to establish the effect of genetic variants identified in genetic studies of long-lived individuals on general health and lifespan using cellular models and, subsequently, model organisms. To this end, I will use CRISPR/Cas9 gene editing to generate transgenic cell lines and mice that harbour genetic variants in candidate genes and pathways identified through GWAS and sequencing studies of long-lived families and individuals. I will subsequently use this information to create a high-throughput screening assay to identify compounds that can pharmacologically recapitulate the observed in vitro effects. As a proof-of-principle, I will start with functional characterisation of rare variants in genes involved in insulin/insulin-like growth factor 1 (IIS) and mammalian target of rapamycin (mTOR) signalling, given the well-known role of these networks in ageing in pre-clinical model organisms.
One of the greatest challenges in exploiting the electron spin for information processing is that it is not a conserved quantity like the electron charge. In addition, spin lifetimes are rather short and correspondingly coherence is quickly lost. This challenge culminates in the coherent manipulation and detection of information from a single spin. Except in a few special systems, so far, single spins cannot be manipulated coherently on the atomic scale, while spin coherence times can only be measured on spin ensembles. A new concept is needed for coherence measurements on arbitrary single spins. Here, the principal investigator (PI) will combine a novel time- and spin-resolved low-temperature scanning tunneling microscope (STM) with the concept of pulsed electron paramagnetic resonance. With this unique and innovative setup, he will be able to address long-standing problems, such as relaxation and coherence times of arbitrary single spin systems on the atomic scale as well as individual spin interactions with the immediate surroundings. Spin readout will be realized through the detection of the absolute spin polarization in the tunneling current by a superconducting tip based on the Meservey-Tedrow-Fulde effect, which the PI has recently demonstrated for the first time in STM. For the coherent excitation, a specially designed pulsed GHz light source will be implemented. The goal is to better understand the spin dynamics and coherence times of single spin systems as well as the spin interactions involved in the decay mechanisms. This will have direct impact on the feasibility of quantum spin information processing with single spin systems on different decoupling surfaces and their scalability at the atomic level. A successful demonstration will enhance the detection limit of spins by several orders of magnitude and fill important missing links in the understanding of spin dynamics and quantum computing with single spins.