Benchmarking reconstructive spectrometer with multi-resonant cavities

Recent years have seen the rapid development of miniaturized reconstructive spectrometers (RSs), yet they still confront a range of technical challenges, such as bandwidth/resolution ratio, sensing speed, and/or power efficiency. Reported RS designs often suffer from insufficient decorrelation between sampling channels, which results in limited compressive sampling efficiency, in essence, due to inadequate engineering of sampling responses. This in turn leads to poor spectral-pixel-to-channel ratios (SPCRs), typically restricted at single digits. So far, there lacks a general guideline for manipulating RS sampling responses for the effectiveness of spectral information acquisition. In this study, we shed light on a fundamental parameter from the compressive sensing theory - the average mutual correlation coefficient v - and provide insight into how it serves as a critical benchmark in RS design with regards to the SPCR and reconstruction accuracy. To this end, we propose a novel RS design with multi-resonant cavities, consisting of a series of partial reflective interfaces. Such multi-cavity configuration offers an expansive parameter space, facilitating the superlative optimization of sampling matrices with minimized v. As a proof-of-concept demonstration, a single-shot, dual-band RS is implemented on a SiN platform, tailored for capturing signature spectral shapes across different wavelength regions, with customized photonic crystal nanobeam mirrors. Experimentally, the device demonstrates an overall operation bandwidth of 270 nm and a <0.5 nm resolution with only 15 sampling channels per band, leading to a record high SPCR of 18.0. Moreover, the proposed multi-cavity design can be readily adapted to various photonic platforms. For instance, we showcase that by employing multi-layer coatings, an ultra-broadband RS can be optimized to exhibit a 700 nm bandwidth with an SPCR of over 100

Holocene climate dynamics derived from pollen record of Jiulongchi wetland in Fanjing Mountain, southwest China

An alpine wetland core was obtained to a depth of 4.0 m from the Fanjing Mountain in southwest China. Sections of the core were dated with C-14 data obtained with high resolution mass spectrometry (AMS), and Holocene climate changes were inferred by categorizing predominant tree and fern vegetation identified from pollen and spore counts at various core depths. The temperature increased during 11.9-8.0 cal ka BP, and the warmest period was during 8.0-4.6 cal ka BP. Then, it gradually became cooler during the late Holocene. Our temperature estimates were in good agreement with the previous studies of the Holocene temperature in the Asian monsoon areas. There were two relatively wet periods of 10.7-8.0 cal ka BP and 4.6-2.6 cal ka BP. There was an asynchronous precipitation trend in the south, north and southwest China, which was probably due to the different monsoon impacts. In East Asian summer monsoon (EASM) area, the monsoon precipitation gradually transgressed northward during the early to middle Holocene and regressed southward during the late Holocene. Our results will be useful to improve the understanding of the coherent spatio-temporal patterns of climate evolution in EASM region in China

Clumped Isotope Analysis of Calcite and Dolomite Mixtures Using Selective Acid Extraction

International audienceAcid extraction methods have been used in the last half century to selectively extract the CO2 produced from different carbonate minerals in mixed samples. However, these methods are often time-consuming and labor intensive. Their application to clumped isotope (Δ47) analysis has not beendemonstrated. We propose here an acid extraction method with phosphoric acid for bulk stable and clumped isotope analysis that treats mixtures of calcite and dolomite the same regardless of the proportionalcomposition. CO2 evolved from calcite is extracted by allowing a reaction with phosphoric acid to proceed for 10 min at 50 ℃. We then extract CO2 evolved from dolomite by rapid ramping the acid temperature from 50 to 90 ℃ and allowing the reaction to complete. The experimental results show that our method yields accurate calcite and dolomite Δ47 values from mixed samples under different proportional compositions. Our method also displays equal or higher accuracy for calcite δ13C and dolomite δ13C and δ18O values from mixtures when compared to previous studies. Our approach exhibits higher sample throughput than previous methods, is adequate for clumped isotopic analysis and simplifies the reaction progression from over 24 h to less than 2 h, while maintaining relatively high isotopic obtaining accuracy. It yet poorly resolves calcite δ18O values, as found with previous methods

Empiric treatment against invasive fungal diseases in febrile neutropenic patients: a systematic review and network meta-analysis

Abstract Background The most optimal antifungal agent for empiric treatment of invasive fungal diseases (IFDs) in febrile neutropenia is controversial. Our objective was evaluate the relative efficacy of antifungals for all-cause mortality, fungal infection-related mortality and treatment response in this population. Methods Pubmed, Embase and Cochrane Library were searched to identify randomized controlled trials (RCTs). Two reviewers performed the quality assessment and extracted data independently. Pairwise meta-analysis and network meta-analysis were conducted to compare the antifungals. Results Seventeen RCTs involving 4583 patients were included. Risk of bias of included studies was moderate. Pairwise meta-analysis indicated the treatment response rate of itraconazole was significantly better than conventional amphotericin B (RR = 1.33, 95%CI 1.10–1.61). Network meta-analysis showed that amphotericin B lipid complex, conventional amphotericin B, liposomal amphotericin B, itraconazole and voriconazole had a significantly lower rate of fungal infection-related mortality than no antifungal treatment. Other differences in outcomes among antifungals were not statistically significant. From the rank probability plot, caspofungin appeared to be the most effective agent for all-cause mortality and fungal infection-related mortality, whereas micafungin tended to be superior for treatment response. The results were stable after excluding RCTs with high risk of bias, whereas micafungin had the lowest fungal infection-related mortality. Conclusions Our results highlighted the necessity of empiric antifungal treatment and indicates that echinocandins appeared to be the most effective agents for empiric treatment of febrile neutropenic patients based on mortality and treatment response. However, more studies are needed to determine the best antifungal agent for empiric treatment. Our systematic review has been prospectively registered in PROSPERO and the registration number was CRD42015026629

Artificial Zinc-Finger Transcription Factor of A20 Suppresses Restenosis in Sprague Dawley Rats after Carotid Injury via the PPARα Pathway

The inhibition of inflammation and vascular smooth muscle cell (VSMC) proliferation is an ideal strategy to suppress intimal hyperplasia after percutaneous transluminal angioplasty (PTA). Evidence has indicated that overexpression of A20 suppresses neointima formation, but its low transfection efficiency limits its application. Hence, we upregulated A20 expression via transfection of rAd.ATF (recombinant adenovirus vector of artificial transcription factor) and rAd.A20 in rat carotid arteries after balloon dilatation (in vivo) and isolated VSMCs (in vitro). In vivo, we found that after rAd.ATF and rAd.A20 transfection, A20 expression was markedly increased, whereas proliferating cell nuclear antigen (PCNA) and nuclear factor κB p65 (NF-κBp65) protein levels were significantly decreased, and intimal hyperplasia and secretion of proinflammatory factors were significantly reduced when compared with empty vector and saline control groups. Most importantly, the rAd.ATF-treated group showed more significant inhibition on intimal hyperplasia and expression of PCNA than the rAd.A20-treated group. In vitro, compared with the control group, transfection of rAd.ATF and rAd.A20 significantly increased A20 expression, which upregulated the proliferator-activated receptor (PPAR) level for both mRNA and protein, and reduced migration and proliferation of VSMCs and lipopolysaccharide (LPS)-induced inflammation. Furthermore, the PPARα agonist GW6471 could partially restore the effect of A20 on VSMCs. Our findings indicate that the ATF of A20 inhibits neointimal hyperplasia and, therefore, constitutes a novel potential alternative to prevent restenosis. Keywords: A20, stroke, PPARα, restenosis, transcription facto

Urbanization-induced warming amplifies population exposure to compound heatwaves but narrows exposure inequality between global North and South cities

Abstract Urban populations face heightened extreme heat risks attributed to urban heat islands and high population densities. Although previous studies have examined global urban population exposure to heatwaves, the influence of urbanization-induced warming is still not quantified. Here, leveraging satellite-derived near-surface air temperature data, we assess the impacts of urbanization-induced warming on heat exposure in 1028 cities worldwide. Additionally, we investigate its role in shaping disparities in heat exposure between global North and South cities. Our findings reveal that urbanization-amplified compound heatwaves exacerbate heat exposure risk in more than 90% of cities, and that this amplification is stronger in high urbanization areas. Moreover, our analysis highlights the potential for overestimating disparities between global North and South cities if urbanization-induced warming is overlooked. The inequality of higher heat exposure in the global South cities than in the global North cities will be narrowed in real scenarios due to more intense urbanization-induced warming in the global North cities. We emphasize the pivotal role of urbanization-induced heatwave intensification in heat exposure assessments and call for its inclusion in future population vulnerability evaluations to extreme heat

Ginseng Rb fraction protects glia, neurons and cognitive function in a rat model of neurodegeneration.

The loss and injury of neurons play an important role in the onset of various neurodegenerative diseases, while both microgliosis and astrocyte loss or dysfunction are significant causes of neuronal degeneration. Previous studies have suggested that an extract enriched panaxadiol saponins from ginseng has more neuroprotective potential than the total saponins of ginseng. The present study investigated whether a fraction of highly purified panaxadiol saponins (termed as Rb fraction) was protective for both glia and neurons, especially GABAergic interneurons, against kainic acid (KA)-induced excitotoxicity in rats. Rats received Rb fraction at 30 mg/kg (i.p.), 40 mg/kg (i.p. or saline followed 40 min later by an intracerebroventricular injection of KA. Acute hippocampal injury was determined at 48 h after KA, and impairment of hippocampus-dependent learning and memory as well as delayed neuronal injury was determined 16 to 21 days later. KA injection produced significant acute hippocampal injuries, including GAD67-positive GABAergic interneuron loss in CA1, paralbumin (PV)-positive GABAergic interneuron loss, pyramidal neuron degeneration and astrocyte damage accompanied with reactive microglia in both CA1 and CA3 regions of the hippocampus. There was also a delayed loss of GAD67-positive interneurons in CA1, CA3, hilus and dentate gyrus. Microgliosis also became more severe 21 days later. Accordingly, KA injection resulted in hippocampus-dependent spatial memory impairment. Interestingly, the pretreatment with Rb fraction at 30 or 40 mg/kg significantly protected the pyramidal neurons and GABAergic interneurons against KA-induced acute excitotoxicity and delayed injury. Rb fraction also prevented memory impairments and protected astrocytes from KA-induced acute excitotoxicity. Additionally, microglial activation, especially the delayed microgliosis, was inhibited by Rb fraction. Overall, this study demonstrated that Rb fraction protected both astrocytes and neurons, especially GABAergic interneurons, and maintained microglial homeostasis against KA-induced excitotoxicity. Therefore, Rb fraction has the potential to prevent and treat neurodegenerative diseases

Benchmarking Reconstructive Spectrometer with Multiresonant Cavities.

Publication status: PublishedRecent years have seen the rapid development of miniaturized reconstructive spectrometers (RSs), yet they still confront a range of technical challenges, such as bandwidth/resolution ratio, sensing speed, and/or power efficiency. Reported RS designs often suffer from insufficient decorrelation between sampling channels, which, in essence, is due to inadequate engineering of sampling responses. This in turn results in poor spectral-pixel-to-channel ratios (SPCRs), typically restricted at single digits. So far, there lacks a general guideline for manipulating RS sampling responses for the effectiveness of spectral information acquisition. In this study, we shed light on a fundamental parameter from the compressive sensing (CS) theory-the average mutual correlation coefficient ν-and provide insight into how it serves as a critical benchmark in RS design. To this end, we propose a novel RS design with multiresonant cavities, consisting of a series of partial reflective interfaces. Such multicavity configuration allows the superlative optimization of sampling matrices to achieve minimized ν. Experimentally, we implement a single-shot, dual-band RS on a SiN platform, realizing an overall operation bandwidth of 270 nm and a <0.5 nm resolution with only 15 sampling channels per band. This leads to a record high SPCR of 18.0. Moreover, the proposed multicavity design can be readily adapted to various photonic platforms, ranging from optical fibers to free-space optics. For instance, we showcase that by employing multilayer coatings, an ultrabroadband RS can be optimized to exhibit a 700 nm bandwidth with an SPCR of over 100