According to their host range, Salmonella enterica can be divided into generalists, host-adapted, and host-specific serovars. The generalist Salmonella enterica serovar Typhimurium causes disease in many animal species but host specific serovars cause disease only in one host. In this study, the hypothesis that macrophages contribute to Salmonella host specificity in vivo was tested in mice. The survival of Typhimurium and the host specific Salmonella enterica serovar Typhi were compared in mouse macrophage cell lines (RAW 264.7 and J774A.1), and murine peritoneal, spleen and bone marrow derived macrophages in vitro. Differences in survival observed for the two serovars in these in vitro studies could not distinguish host specific from generalist serovars. When BALB/c mice were infected in vivo i.p., equivalent levels of Typhimurium could be found in the peritoneum 0.5 and 4 hr post-infection but Typhi decreased drastically between these two time points. Both Typhi and Typhimurium induced neutrophil influx into the peritoneum and macrophages disappeared with both serovars. With either serovar, macrophages were shown to be the major cell type containing internalized bacteria after both 0.5 and 4 hr of infection. However, significantly lower numbers of viable Typhi were recovered from macrophages infected in vivo than Typhimurium. These data showed that macrophages were able to distinguish Typhi from Typhimurium when infected in vivo, suggesting that the in vivo environment is important for macrophages to play an important role in Salmonella host specificity

In this dissertation I used Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) to recover crustal deformation caused by earthquake cycle processes. The studied areas span three different types of tectonic boundaries: a continental thrust earthquake (M7.9 Wenchuan, China) at the eastern margin of the Tibet plateau, a mega-thrust earthquake (M8.8 Maule, Chile) at the Chile subduction zone, and the interseismic deformation of the San Andreas Fault System (SAFS). A new L-band radar onboard a Japanese satellite ALOS allows us to image high-resolution surface deformation in vegetated areas, which is not possible with older C-band radar systems. In particular, both the Wenchuan and Maule InSAR analyses involved L-band ScanSAR interferometry which had not been attempted before. I integrated a large InSAR dataset with dense GPS networks over the entire SAFS. The integration approach features combining the long- wavelength deformation from GPS with the short-wavelength deformation from InSAR through a physical model. The recovered fine-scale surface deformation leads us to better understand the underlying earthquake cycle processes. The geodetic slip inversion reveals that the fault slip of the Wenchuan earthquake is maximum near the surface and decreases with depth. The coseismic slip model of the Maule earthquake constrains the down-dip extent of the fault slip to be at 45 km depth, similar to the Moho depth. I inverted for the slip rate on 51 major faults of the SAFS using Green's functions for a 3-dimensional earthquake cycle model that includes kinematically prescribed slip events for the past earthquakes since the year 1000. A 60 km thick plate model with effective viscosity of 10¹⁹ Pa · s is preferred based on the geodetic and geological observations. The slip rates recovered from the plate models are compared to the half- space model. The InSAR observation reveals that the creeping section of the SAFS is partially locked. This high-resolution deformation model will refine the moment accumulation rates and shear strain rates, which are not well resolved by previous models

Under suitable assumptions, the quantum-phase-estimation (QPE) algorithm is able to achieve Heisenberg-limited precision scaling in estimating the ground-state energy. However, QPE requires a large number of ancilla qubits and a large circuit depth, as well as the ability to perform inverse quantum Fourier transform, making it expensive to implement on an early fault-tolerant quantum computer. We propose an alternative method to estimate the ground-state energy of a Hamiltonian with Heisenberg-limited precision scaling, which employs a simple quantum circuit with one ancilla qubit, and a classical postprocessing procedure. Besides the ground-state energy, our algorithm also produces an approximate cumulative distribution function of the spectral measure, which can be used to compute other spectral properties of the Hamiltonian.

This article examines the recollection of Qin demise memories of medieval Chinese elites, arguing that they took the “Qin demise” notion as a means to achieve their respective political agendas. The Qin dynasty was the first empire that accomplished the unification of all-under-heaven in Chinese history; however, it collapsed in fifteen years. When analysing the causes of the Qin collapse, a controversial question catches enduring attention: To what extent does the system of administration account for the Qin demise? This question has led to an unsettled debate over the respective merits of the investiture- and commandery-county systems among Chinese literati for more than two millennia. This paper historicizes the debate about administrative system from Wei to mid-Tang, during which transitions of regimes occurred frequently. To examine this debate, the discourses of five intellectuals are chosen chronologically. By studying their memories pertaining to the reasons behind the Qin demise, this paper compares their attitudes to different administrative institutions and attempts to explain the underlying ideologies and historical backgrounds. In the end, I will present a unique mnemonic pattern across time, based on the elites’ discourses.

Staphylococcus argenteus infection was initially described in Aboriginal patients in the Northern Territories of Australia as a predominant cause of skin infections and is rare outside Southeast Asia. A first well-characterized case of S. argenteus infection has now been described in the United States, involving a recurrent hemodialysis catheter infection, in which unstable daptomycin resistance evolved during daptomycin therapy. The unique colonial pigmentation of S. argenteus isolates in strains otherwise identified as Staphylococcus aureus is noteworthy.

Recent advancements in small RNA sequencing have unveiled a previously hidden world of regulatory small noncoding RNAs (sncRNAs) that extend beyond the well-studied small interfering RNAs, microRNAs, and piwi-interacting RNAs. This exploration, starting with tRNA-derived small RNAs, has led to the discovery of a diverse universe of sncRNAs derived from various longer structured RNAs such as rRNAs, small nucleolar RNAs, small nuclear RNAs, Y RNAs, and vault RNAs, with exciting uncharted functional possibilities. In this perspective, we discuss the emerging functional principles of sncRNAs beyond the well-known RNAi-like mechanisms, focusing on those that operate independent of linear sequence complementarity but rather function in an aptamer-like fashion. Aptamers use 3D structure for specific interactions with ligands and are modulated by RNA modifications and subcellular environments. Given that aptamer-like sncRNA functions are widespread and present in species lacking RNAi, they may represent an ancient functional principle that predates RNAi. We propose a rethinking of the origin of RNAi and its relationship with these aptamer-like functions in sncRNAs and how these complementary mechanisms shape biological processes. Lastly, the aptamer-like function of sncRNAs highlights the need for caution in using small RNA mimics in research and therapeutics, as their specificity is not restricted solely to linear sequence.