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In remote sensing, numerous unlabeled images are continuously accumulated over time, and it is difficult to annotate all the data. Therefore, a self-supervised learning technique that can improve the recognition rate using unlabeled data will be useful for remote sensing. This letter presents contrastive self-supervised learning with smoothed representation for remote sensing based on the SimCLR framework. In self-supervised learning for remote sensing, the well-known characteristic that images within a short distance might be semantically similar is usually used. Our algorithm is based on this knowledge, and it simultaneously utilizes several neighboring images as a positive pair of the anchor image, unlike existing methods such as Tile2Vec. Furthermore, MoCo and SimCLR, which are among the state-of-the-art self-supervised learning approaches, only use two augmented views of the single-input image, but our proposed approach uses multiple-input images and averages their representations (e.g., smoothed representation). Consequently, the proposed approach outperforms state-of-the-art self-supervised learning methods, such as Tile2Vec, MoCo, and SimCLR, in the cropland data layer (CDL), RESISC-45, UCMerced, and EuroSAT data sets. The proposed approach is comparable to the pretrained ImageNet model in the CDL classification task.

Especially through the release from anthropogenic sources, there is growing concern about human exposure to ultrafine particulate matter (UFP). Inhalation of UFP is associated with respiratory diseases such as asthma, pulmonary fibrosis and lung cancer, but their mechanisms of action are still vastly unknown. In this study we aimed to address the question whether the physical characteristics of UFP contribute most to their toxicity or whether the particles primarily act as carriers of toxic chemicals. For this scope, two distinct UFP aerosols with low or high content of semi-volatile organic compounds (SVOC) but comparable sizes were produced by a combustion aerosol standard soot generator and investigated regarding their acute (geno)-toxic potential in a cell model consisting of alveolar epithelial cells, macrophages, and fibroblasts at the air-liquid interface. Low SVOC UFP induced an increased cytotoxicity accompanied by a reduced cell number of epithelial cells and a decreased metabolic activity of fibroblasts. Furthermore, an increased intracellular release of reactive oxygen species (ROS) was observed after low SVOC UFP treatment, which resulted in a depletion of intracellular glutathione. The increased ROS release could be causative for the observed secondary genotoxicity in fibroblasts exclusively detected after exposure to low organic content UFP. High SVOC UFP did not impact cell viability, but an increased DNA damage could be detected in epithelial cells. All in all, UFP with low organic content seem to induce a stronger acute cytotoxic and oxidative stress response in epithelial cells, which might cause secondary effects in fibroblasts.

The emissions of marine diesel engines have gained both global and regional attentions because of their impact on human health and climate change. To reduce ship emissions, the International Maritime Organization capped the fuel sulfur content of marine fuels. Consequently, either low-sulfur fuels or additional exhaust gas cleaning devices for the reduction in sulfur dioxide (SO2) emissions became mandatory. Although a wet scrubber reduces the amount of SO2 significantly, there is still a need to consider the reduction in particle emissions directly. We present data on the particle removal efficiency of a scrubber regarding particle number and mass concentration with different marine fuel types, marine gas oil, and two heavy fuel oils (HFOs). An open-loop sulfur scrubber was installed in the exhaust line of a marine diesel test engine. Fine particulate matter was comprehensively characterized in terms of its physical and chemical properties. The wet scrubber led up to a 40% reduction in particle number, whereas a reduction in particle mass emissions was not generally determined. We observed a shift in the size distribution by the scrubber to larger particle diameters when the engine was operated on conventional HFOs. The reduction in particle number concentrations and shift in particle size were caused by the coagulation of soot particles and formation/growing of sulfur-containing particles. Combining the scrubber with a wet electrostatic precipitator as an additional abatement system showed a reduction in particle number and mass emission factors by >98%. Therefore, the application of a wet scrubber for the after-treatment of marine fuel oil combustion will reduce SO2 emissions, but it does not substantially affect the number and mass concentration of respirable particulate matters. To reduce particle emission, the scrubber should be combined with additional abatement systems.

BACKGROUND: Secondary organic aerosols (SOAs) formed from anthropogenic or biogenic gaseous precursors in the atmosphere substantially contribute to the ambient fine particulate matter [PM ≤2.5μm in aerodynamic diameter (PM2.5)] burden, which has been associated with adverse human health effects. However, there is only limited evidence on their differential toxicological impact. OBJECTIVES: We aimed to discriminate toxicological effects of aerosols generated by atmospheric aging on combustion soot particles (SPs) of gaseous biogenic (β-pinene) or anthropogenic (naphthalene) precursors in two different lung cell models exposed at the air-liquid interface (ALI). METHODS: Mono- or cocultures of lung epithelial cells (A549) and endothelial cells (EA.hy926) were exposed at the ALI for 4 h to different aerosol concentrations of a photochemically aged mixture of primary combustion SP and β-pinene (SOAβPIN-SP) or naphthalene (SOANAP-SP). The internally mixed soot/SOA particles were comprehensively characterized in terms of their physical and chemical properties. We conducted toxicity tests to determine cytotoxicity, intracellular oxidative stress, primary and secondary genotoxicity, as well as inflammatory and angiogenic effects. RESULTS: We observed considerable toxicity-related outcomes in cells treated with either SOA type. Greater adverse effects were measured for SOANAP-SP compared with SOAβPIN-SP in both cell models, whereas the nano-sized soot cores alone showed only minor effects. At the functional level, we found that SOANAP-SP augmented the secretion of malondialdehyde and interleukin-8 and may have induced the activation of endothelial cells in the coculture system. This activation was confirmed by comet assay, suggesting secondary genotoxicity and greater angiogenic potential. Chemical characterization of PM revealed distinct qualitative differences in the composition of the two secondary aerosol types. DISCUSSION: In this study using A549 and EA.hy926 cells exposed at ALI, SOA compounds had greater toxicity than primary SPs. Photochemical aging of naphthalene was associated with the formation of more oxidized, more aromatic SOAs with a higher oxidative potential and toxicity compared with β-pinene. Thus, we conclude that the influence of atmospheric chemistry on the chemical PM composition plays a crucial role for the adverse health outcome of emissions. https://doi.org/10.1289/EHP9413.

The United States Medical Licensing Examination (USMLE) Step 1 examination will transition from graded to pass/fail scoring starting no earlier than January 2022. Orthopedic surgery residency programs will need to adapt to these changes. The goal of this study was to investigate the perceptions of orthopedic surgery residency program directors on the change of Step 1 from a graded to a pass/fail examination. We also investigated how the change would affect the other factors that are typically considered in the selection of orthopedic surgery residents. A survey was distributed to 161 directors of allopathic orthopedic surgery programs. Contact information was obtained from a national database. Of those contacted, 75 (46.6%) program directors responded. Most (85.3%) did not support the pass/fail change. Most believe that greater importance will be placed on the Step 2 Clinical Knowledge examination (96.0%), audition elective with their department (84.0%), personal knowledge of the applicant (78.7%), grades (74.7%), letters of recommendation from recognizable orthopedic surgeons (74.7%), and Alpha Omega Alpha status (69.3%). Most also believe that this change will advantage allopathic students who attend highly regarded schools (58.7%). Most of the program directors support a graded preclinical curriculum (69.3%) and caps on the number of orthopedic surgery residency applications (70.7%). Although most orthopedic surgery program directors disagree with the change to a pass/fail Step 1 examination, residency programs will need to reevaluate how they screen applicants for an interview once the scored Step 1 is no longer available. With this change, other factors, such as Step 2 score, audition rotations, and grades in clerkships, will be emphasized more heavily. [ Orthopedics . 2022;45(1):e30–e34.]

United States Medical Licensing Examination Step 1 will transition from numeric grading to pass/fail, sometime after January 2022. The aim of this study was to compare how program directors in orthopaedics and internal medicine perceive a pass/fail Step 1 will impact the residency application process.A 27-item survey was distributed through REDCap to 161 U.S. orthopaedic residency program directors and 548 U.S. internal medicine residency program directors. Program director emails were obtained from the American Medical Association's Fellowship and Residency Electronic Interactive Database.We received 58 (36.0%) orthopaedic and 125 (22.8%) internal medicine program director responses. The majority of both groups disagree with the change to pass/fail, and felt that the decision was not transparent. Both groups believe that the Step 2 Clinical Knowledge exam and clerkship grades will take on more importance. Compared to internal medicine PDs, orthopaedic PDs were significantly more likely to emphasize research, letters of recommendation from known faculty, Alpha Omega Alpha membership, leadership/extracurricular activities, audition elective rotations, and personal knowledge of the applicant. Both groups believe that allopathic students from less prestigious medical schools, osteopathic students, and international medical graduates will be disadvantaged. Orthopaedic and internal medicine program directors agree that medical schools should adopt a graded pre-clinical curriculum, and that there should be a cap on the number of residency applications a student can submit.Orthopaedic and internal medicine program directors disagree with the change of Step 1 to pass/fail. They also believe that this transition will make the match process more difficult, and disadvantage students from less highly-regarded medical schools. Both groups will rely more heavily on the Step 2 clinical knowledge exam score, but orthopaedics will place more importance on research, letters of recommendation, Alpha Omega Alpha membership, leadership/extracurricular activities, personal knowledge of the applicant, and audition electives.

Bonding between reinforcing bars and cement was enhanced using multi-walled carbon nanotubes (MWCNTs). To investigate the bonding behavior between the composites and a reinforcing bar, 20 bond strength test specimens were fabricated and a pullout test was performed. Additionally, the compressive strengths of MWCNT-cementitious composites were evaluated with different MWCNT concentrations. To analyze the internal structural mechanisms of MWCNT cementitious composites, mercury intrusion porosimetry (MIP) and field emission scanning electron microscopy (FE-SEM) were conducted. The results demonstrated that 0.5 wt% MWCNTs increased the compressive strength of the cementitious composites and enhanced the bonding between the cement composite and the reinforcing bar.

Coloration plays a crucial role in the social communication and survival of organisms. Multidisciplinary studies have been conducted to elucidate the correlation between coloration and melanin biosynthesis (referred as melanogenesis). The multi-copper enzyme tyrosinase catalyzes the first two steps of melanogenesis for coloration in teleosts. Due to the increasing demand of tyrosinase inhibitors for the production of skin whitening cosmetics, hypopigmentation pharmaceuticals, and anti-browning agents, a large number of natural and synthetic inhibitors have been developed over the past few decades. Although a number of previous studies have focused on human use and toxicity, such as the increased cytotoxic effects of ROS-generating compounds, their ecotoxicological impacts on aquatic organisms are still poorly understood. Hence, the focus of the present review is to describe the role of coloration in teleosts as well as potential ecotoxicological effects elicited by exposure to tyrosinase inhibitors. Furthermore, this review introduces our recently registered adverse outcome pathway (AOP) related to tyrosinase inhibition and population decline in teleosts.

To improve the mechanical strength of cement materials used in infrastructure, this study investigates cementitious composites containing multi walled carbon nanotubes (MWCNTs), fabricated using different mixing methods and MWCNT concentrations. A total of 30 MWCNT cementitious composite specimens were fabricated, and the compressive strengths and heating performances of the MWCNT cementitious composites were tested. Mercury intrusion porosimetry tests were conducted to assess porosity decreases in the MWCNT cementitious specimens, and field emission scanning electron microscopy images were obtained to elucidate the internal structures of the composites.

Drawing on the theoretical framework of transaction cost theory and social exchange theory, this study empirically examines factors affecting the likelihood and the level of interlocal expenditure for 11 service types in a panel of 695 American cities, with populations over 20,000, during the time period of 1990–2000. The findings indicate that elements of transaction costs risks (asset specificity and measurement difficulty) affect both the likelihood and the level of interlocal cooperation. It also shows that the level of trust does the same. However, it suggests that the perceived transaction risks may vary depending on factors affecting local managers' perception of transaction risks. This will further affect the likelihood and the level of interlocal cooperation.

Carrier transport and recombination mechanisms in Cu 2 O–ZnO heterojunction thin film solar cells were investigated through an analysis of their current–voltage characteristics in the dark and under various illumination intensities, as a function of temperature between 100 K and 295 K. The Cu 2 O–ZnO heterojunction solar cells were prepared by metal organic chemical vapor deposition of Cu 2 O on ZnO films sputtered on transparent conducting oxide coated glass substrates. Activation energies extracted from the temperature dependence of the J–V characteristics reveals that interface recombination is the dominant carrier transport mechanism. Tunneling across an interfacial barrier also plays an important role in current flow and a thin TiO 2 buffer layer reduces tunneling. A high open circuit voltage at low temperature (~ 0.9 V at around 100 K) indicates that Cu 2 O–ZnO heterojunction solar cells have high potential as solar cells if the recombination and tunneling at the interface can be suppressed at room temperature.