Maps preserving operator pairs whose products are projections

AbstractLet B(H) be the algebra of all bounded linear operators on a complex Hilbert space H with dimH⩾2. It is proved that a surjective map φ on B(H) preserves operator pairs whose products are nonzero projections in both directions if and only if there is a unitary or an anti-unitary operator U on H such that φ(A)=λU∗AU for all A in B(H) for some constants λ with λ2=1. Related results for surjective maps preserving operator pairs whose triple Jordan products are nonzero projections in both directions are also obtained. These show that the operator pairs whose products or triple Jordan products are nonzero projections are isometric invariants of B(H)

Measuring cell deformation by microfluidics

Microfluidics is an increasingly popular method for studying cell deformation, with various applications in fields such as cell biology, biophysics, and medical research. Characterizing cell deformation offers insights into fundamental cell processes, such as migration, division, and signaling. This review summarizes recent advances in microfluidic techniques for measuring cellular deformation, including the different types of microfluidic devices and methods used to induce cell deformation. Recent applications of microfluidics-based approaches for studying cell deformation are highlighted. Compared to traditional methods, microfluidic chips can control the direction and velocity of cell flow by establishing microfluidic channels and microcolumn arrays, enabling the measurement of cell shape changes. Overall, microfluidics-based approaches provide a powerful platform for studying cell deformation. It is expected that future developments will lead to more intelligent and diverse microfluidic chips, further promoting the application of microfluidics-based methods in biomedical research, providing more effective tools for disease diagnosis, drug screening, and treatment

Preparation of graphene oxide decorated Fe3O4@SiO2 nanocomposites with superior adsorption capacity and SERS detection for organic dyes

The fast detection and removal of organic dyes from contaminated water has become an urgent environmental issue due to their high toxicity, chemical stability, and low biodegradability. In this paper, we have developed graphene oxide decorated Fe3O4@SiO2 (Fe3O4@SiO2-GO) as a novel adsorbent aiming at the rapid adsorption and trace analysis of organic dyes followed by surface enhanced Raman scattering (SERS). The structure and morphology of the nanocomposites were characterized by transmission electron microscopy (TEM), Fourier infrared spectrometry (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The obtained nanocomposites were used to adsorb methylene blue (MB) in aqueous solution based on π-π stacking interaction and electrostatic attraction between MB and GO, and the adsorption behaviors of MB were investigated. Moreover, the obtained nanocomposites with adsorbed dyes were separated from the solution and loaded with silver nanoparticles for SERS detection. These nanocomposites showed superior SERS sensitivity and the lowest detectable concentration was 1.0 × 10-7 M

Silver nanoprism-loaded eggshell membrane: a facile platform for in situ SERS monitoring of catalytic reactions

We reported the fabrication of an in situ surface-enhanced Raman scattering (SERS) monitoring platform, comprised of a porous eggshell membrane (ESM) bioscaffold loaded with Ag nanoprism via an electrostatic self-assembly approach. The localized surface plasmon resonance (LSPR) property of silver nanoprism leads to the blue color of the treated ESMs. UV-vis diffuse reflectance spectroscopy, scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements were employed to observe the microstructure and surface property of Ag nanoprisms on the ESMs. The silver nanoprism-loaded eggshell membrane (AgNP@ESM) exhibited strong catalytic activity for the reduction of 4-nitrophenol by sodium borohydride (NaBH4) and it can be easily recovered and reused for more than six cycles. Significantly, the composites also display excellent SERS efficiency, allowing the in situ SERS monitoring of molecular transformation in heterogeneous catalysis. The results indicate that the AgNP@ESM biocomposite can achieve both SERS and catalytic functionalities simultaneously in a single entity with high performance, which promotes the potential applications of ESM modified with functional materials

The relationship between oxygen therapy, drug therapy, and COVID-19 mortality

Since December, 2019, Wuhan, China, has experienced an outbreak of coronavirus disease 2019 (COVID-19). We conducted a retrospective study of COVID-19 inpatients in Wuhan Pulmonary Hospital (Wuhan, China) from January 1 to February 29, 2020. The subjects were divided into four groups due to different treatment regimes. We used the Kaplan–Meier method to determine the cumulative rates of in-hospital death and the Cox proportional hazard model to calculate the risk factors and corresponding hazard ratios. A total of 185 patients were included in this study. The median age of the patients was 62 years, including 94 men and 91 women. Kaplan–Meier analysis demonstrated that mortality was higher in older patients, higher in men, and lower in the low-flow oxygen therapy group. Body mass index (BMI) had no influence on mortality, as well as high flow oxygen therapy, Lopinavir–ritonavir (LPV/r) therapy, and the interferon-alpha add LPV/r therapy. Cox proportional hazard regression confirmed that the low flow oxygen therapy was independent protective factor for in-hospital death after adjusting for age, gender, and BMI. In conclusion, the mortality was higher in older patients, higher in men, and lower in the low-flow oxygen therapy group. BMI had no influence on mortality, as well as high flow oxygen therapy, LPV/r therapy, and interferon-alpha add LPV/r therapy

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Essays on the economic impact of religiosity and family ties

This thesis seeks an understanding of how cultural factors may affect economic behavior and drive aggregate outcomes. It comprises 3 self-contained essays that explore the link between the strength of social institutions and economic issues, with the purpose of providing insights from an empirical angle to yield policy-relevant research outcomes. We focus on the dominance of two social institutions in this thesis – religion and family, both of which are historically common foundations of human cultures throughout the world. We investigate how variations in the level of religiosity and the strength of family ties may affect attitudes towards immigration, as well as the extent of financial inclusiveness. In chapter 1, we look at the link between religiosity and attitudes towards immigration. Immigration is a contentious area in the public sphere today, with communities having increasingly polarized outlooks towards pro-immigration policies in many developed countries. The recent literature argues that non-economic social and cultural factors explain a substantial share of the variation in individual attitudes towards immigration. However, it is still unclear what these non-economic factors are. This chapter argues that the intensity of religious beliefs and the extent of the religious social network are important determinants of immigration attitudes. Using both individual and subnational regional analyses, we find robust evidence that stronger religious beliefs are linked to greater hostility towards pro-immigration policies. To deal with endogeneity concerns, we employ an instrumental variable that measures a subnational district’s exposure to recent significant earthquakes. Financial inclusion, conceptually defined as the access and usage of formal financial services, is widely linked to poverty alleviation and is a policy objective for many governments worldwide. In chapter 2, we explore the notion that the preference for specific sources of finance stems from the extent of social capital that is available. More specifically, we argue that the strength of family ties determines the adoption and usage of services provided by financial institutions. Using both international and the U.S. data, we find significant evidence indicating that stronger family ties are linked to a lower ownership rate of financial accounts and usage of formal financial services. To identify exogenous variation in the strength of family ties, we employ an index representing the country’s suitability for wheat cultivation at the cross-country level and we examine the effect of inter-generational transmission in the strength family ties through a sample of second-generation immigrants in the US. Chapter 3 estimates the impact of religiosity on financial inclusiveness. We argue that the intensity of religious beliefs and practices can impose informal constraints on our preferences, which in turn affect the composition of incentives and financial choices within societies. Religiosity may also play a role in defining societal norms and influence the development of financial sector. Our results suggest that higher levels of religiosity are associated with lower adoption and usage of formal financial services today. This is observed across U.S. states and across different countries, even after accounting for important cultural and geographical factors as well as measures of economic development. We employ a measure of historical disease prevalence as the main instrumental variable in our analyses and conduct over-identification tests using exposure to natural hazards as additional instruments. At the country level, we also implement a bounds test by Conley, Hansen, and Rossi (2012) to check that the IV results are likely to hold in the case that the exclusion restriction condition is violated.Doctor of Philosoph

Cooling Effect of Crushed Rock-Based Embankment along the Chaidaer-Muli Railway

This paper presents an experimental study of the cooling effect of crushed rock-based embankment on slope wetlands along the Chaidaer-Muli Railway. The result shows that only the embankment shady side can be effectively cooled down in a warm permafrost region and the crushed rock-based embankment can cool the entire embankment in a cold permafrost region. The crushed rock-based embankment cannot eliminate the problems from the south-north slope. Slope wetland can influence the temperature field of the crushed rock-based embankment. On the uphill side, it will lead to degradation in some cases and development of permafrost in other cases, which depends on the topsoil water content and ground surface runoff. On the downhill side, it always leads to the warming of permafrost. For crushed rock-based embankment constructed on slope wetlands, it is necessary to adopt other stronger measures to eliminate the sunny-shady slope problems