18 research outputs found

    Magnetic Exciton-Polariton with Strongly Coupled Atomic and Photonic Anisotropies

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    Anisotropy plays a key role in science and engineering. However, the interplay between the material and engineered photonic anisotropies has hardly been explored due to the vastly different length scales. Here we demonstrate a matter-light hybrid system, exciton-polaritons in a 2D antiferromagnet, CrSBr, coupled with an anisotropic photonic crystal (PC) cavity, where the spin, atomic lattice, and photonic lattices anisotropies are strongly correlated, giving rise to unusual properties of the hybrid system and new possibilities of tuning. We show exceptionally strong coupling between engineered anisotropic optical modes and anisotropic excitons in CrSBr, which is stable against excitation densities a few orders of magnitude higher than polaritons in isotropic materials. Moreover, the polaritons feature a highly anisotropic polarization tunable by tens of degrees by controlling the matter-light coupling via, for instance, spatial alignment between the material and photonic lattices, magnetic field, temperature, cavity detuning and cavity quality-factors. The demonstrated system provides a prototype where atomic- and photonic-scale orders strongly couple, opening opportunities of photonic engineering of quantum materials and novel photonic devices, such as compact, on-chip polarized light source and polariton laser

    Ferro-rotational domain walls revealed by electric quadrupole second harmonic generation microscopy

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    Domain walls are ubiquitous in materials that undergo phase transitions driven by spontaneous symmetry breaking. Domain walls in ferroics and multiferroics have received tremendous attention recently due to their emergent properties distinct from their domain counterparts, for example, their high mobility and controllability, as well as their potential applications in nanoelectronics. However, it is extremely challenging to detect, visualize and study the ferro-rotational (FR) domain walls because the FR order, in contrast to ferromagnetism (FM) and ferroelectricity (FE), is invariant under both the spatial-inversion and the time-reversal operations and thus hardly couple with conventional experimental probes. Here, an FR candidate NiTiO3\mathrm{NiTiO_{3}} is investigated by ultrasensitive electric quadrupole (EQ) second harmonic generation rotational anisotropy (SHG RA) to probe the point symmetries of the two degenerate FR domain states, showing their relation by the vertical mirror operations that are broken below the FR critical temperature. We then visualize the real-space FR domains by scanning EQ SHG microscopy, and further resolve the FR domain walls by revealing a suppressed SHG intensity at domain walls. By taking local EQ SHG RA measurements, we show the restoration of the mirror symmetry at FR domain walls and prove their unconventional nonpolar nature. Our findings not only provide a comprehensive insight into FR domain walls, but also demonstrate a unique and powerful tool for future studies on domain walls of unconventional ferroics, both of which pave the way towards future manipulations and applications of FR domain walls

    Stormwater Analysis and Water Quality Assessment of Urban Areas

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    4400011482, PIT WO 14Salt is widely used for road deicing purpose in winter, and salt application could raise stream chloride level and leads to deterioration of water quality. This study represents the first steps toward developing a comprehensive understanding of how the streams chloride levels are impacted by the salt operation. Toward this goal, this study developed a procedure for the flow path modeling of urban watersheds and applied it to two sites in Pittsburgh, PA, which are potentially susceptible to road salt application by PennDOT. The procedure was used in identifying areas contributing flows to PennDOT right-of-way, and vice versa. This study further took stream water quality samples during non-winter months for establishing baselines and during the winters of 2017 and 2018. Results show that over the non-winter months, the baseline stream chloride concentration has already exceeded criteria continuous concentration most of the time, but lies below the criteria maximum concentration of the environmental regulation. Test results on winter samples show that stream chloride concentration has risen following salt application after snow events, and has exceeded the criteria maximum concentration. The study also shows how surface model of different detail levels would affect the identified contributing areas related to target watersheds, and the importance of properly incorporating roadway features such as curves and bridges

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    An Investigation of Interactions Between Plants and Hydrological Processes with Emphasis on Droughts Using A New Coupled Ecohydrological and Biogeochemical Model

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    Understanding interactions between plants and soil water is of paramount importance for constructing a comprehensive picture of how climate change could affect the hydrological response and how plants adapt to these changes. This study focuses on drought impacts since it is one type of extreme weather brought about by the climate change with devastating effects: how the drought affects plants and, conversely, how plants’ responses, in turn, affect the drought’s impacts. This study investigates impacts of droughts on plant growth associated with hydraulic redistribution, re-infiltration, surface and groundwater interactions, and other hydrological processes governed by the mechanism of plant optimality—plants optimize their use of available resources. This is achieved by coupling VIC+, an extended version of the Three-Layer Variable Infiltration Capacity model, with a terrestrial biogeochemical model--the Carnegie Ames Stanford Approach model of carbon, nitrogen, and phosphorus (CASA-CNP), and with a multiscale routing model as well. The VIC+ model is extended in this work to include the optimality theory in representing the behavior of plant stomatal conductance which plays a pivotal role in the soil-plant-atmosphere system. Specifically, the modeling strategy presented in Luo et al. (2013) of simultaneously using multiple plausible expressions, derived from different perspectives, in representing the same processes is employed to represent the plants’ stomatal conductance and enforcing them together with an optimality rule and a semi-empirical expression. Results in this study illustrate that such a modeling approach makes the new coupled model capable of representing the tight interactions between plants and hydrological processes with much less uncertainties. The coupled routing model makes it possible to consider the re-infiltration process along the flow routing paths. By integrating CASA-CNP into VIC+, one can investigate how drought affects the various interacting processes simultaneously. Using the new coupled ecohydrological and biogeochemical model, various scenario simulations have been conducted with different temporal distributions of precipitation intensities and durations but all with the same total precipitation. Results obtained demonstrate that: (1) the re-infiltration and plant optimality have significant impacts to the plant and water, energy budgets; and (2) the soil moisture is critical for plant mortality and plant regrowth

    Spatial distribution of ammonia-oxidizing archaea and bacteria across eight freshwater lakes in sediments from Jiangsu of China

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    Ammonia-oxidizingarchaea (AOA) and ammonia-oxidizing bacteria (AOB) play an important role innitrogen transformation in freshwater sediments. However, it is still unclear towhat extent the distribution patterns of these microorganisms are affected bythe freshwater sediment across a large geographical scale. This study wasdesigned to gain insight into the heterogeneity distribution of AOA and AOB in32 freshwater sediments from a wide range of ecologic types. Real-time quantitative polymerasechain reaction PCR(qPCR) combined with the terminal restrictionfragment length polymorphism(T-RFLP) were employed to characterize the abundance, diversity, and communitystructure of the AOA and AOB in 32 freshwater sediments. AOA and AOB wereubiquitous in all sediments, and archaeal amoA far outnumbered bacterial amoA inmost sediments with lower organic matters. The abundance of AOA and AOB did notvary with the freshwater ecological type (macrophyte dominated region and algaedominated region). Based on  the T-RFLP of an amoA gene, this research found that organicmatters in pore water rather than other factors affect the AOA communitystructure in sediments, while the AOB were not significantly different in thefreshwater sediments. Phylogenetic analysis showed that all archaeal amoAsequences fell within either the Crenarchaeotal Group (CG) I.1b or the CGI.1asubgroup, and all AOB clustered with genus Nitrosomonas or Nitrosospira. The data obtained inthis study elucidates the role of ammonia-oxidizing archaea andammonia-oxidizing bacteria in the nitrogen cycle of freshwater ecosystems

    Effect of acupoint hot compress on postpartum urinary retention after vaginal delivery: a randomized clinical trial

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    Importance: acupoint hot compress during the early postpartum period may benefit patients after a vaginal delivery, but the evidence of this effect is limited.Objective: to assess whether acupoint hot compress involving the abdominal, lumbosacral, and plantar regions could reduce the incidence of postpartum urinary retention, relieve postpartum uterine contraction pain, prevent emotional disorders, and promote lactation.Design, setting, and participants: this multicenter randomized clinical trial was conducted at 12 hospitals in China. Pregnant patients were screened for eligibility (n = 13 949) and enrolled after vaginal delivery (n = 1200) between January 17 and August 15, 2021; data collection was completed on August 18, 2021. After vaginal delivery, these participants were randomized 1:1 to either the intervention group or control group. Statistical analysis was based on per-protocol population.Interventions: participants in the control group received routine postpartum care. Participants in the intervention group received routine postpartum care plus 3 sessions of a 4-hour acupoint hot compress involving the abdominal, lumbosacral, and plantar regions within 30 minutes, 24 hours, and 48 hours after delivery.Main outcomes and measures: the primary outcome was the incidence of postpartum urinary retention, defined as the first urination occurring more than 6.5 hours after delivery and/or use of an indwelling catheter within 72 hours after delivery. The secondary outcomes were postpartum uterine contraction pain intensity (assessed with the visual analog scale [VAS]), depressive symptoms (assessed with the Edinburgh Postnatal Depression Scale), and lactation conditions (including lactation initiation time, breastfeeding milk volume, feeding mood and times, and newborn weight).Results: of the 1200 participants randomized, 1085 completed the study (537 in the intervention group and 548 in the control group, with a median [IQR] age of 26.0 [24.0-29.0] years). Participants in the intervention group compared with the control group had significantly decreased incidence of postpartum urinary retention (relative risk [RR], 0.58; 95% CI, 0.35-0.98; P = .03); improved postpartum uterine contraction pain when measured at 6.5 hours (median [IQR] VAS score, 1 [1-2] vs 2 [1-2]; P &lt; .001), 28.5 hours (median [IQR] VAS score, 1 [0-1] vs 1 [1-2]; P &lt; .001), 52.5 hours (median [IQR] VAS score, 1 [0-1] vs 1 [0-1]; P &lt; .001), and 76.5 hours (median [IQR] VAS score, 0 [0-1] vs 0 [0-1]; P = .01) after delivery; reduced depressive symptoms (RR, 0.73; 95% CI, 0.54-0.98; P = .01); and increased breastfeeding milk volume measured at 28.5, 52.5, and 76.5 hours after delivery. No adverse events occurred in either of the 2 groups.Conclusions and relevance: results of this trial showed that acupoint hot compress after vaginal delivery decreased postpartum urinary retention, uterine contraction pain, and depressive symptoms and increased breastfeeding milk volume. Acupoint hot compress may be considered as an adjunctive intervention in postnatal care that meets patient self-care needs.Trial registration: Chinese Clinical Trial Registry Identifier: ChiCTR2000038417</p
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