Development and validation of a patient-specific model to predict postoperative SIRS in older patients: A two-center study

IntroductionPostoperative systemic inflammatory response syndrome (SIRS) is common in surgical patients especially in older patients, and the geriatric population with SIRS is more susceptible to sepsis, MODS, and even death. We aimed to develop and validate a model for predicting postoperative SIRS in older patients.MethodsPatients aged ≥65 years who underwent general anesthesia in two centers of Third Affiliated Hospital of Sun Yat-sen University from January 2015 to September 2020 were included. The cohort was divided into training and validation cohorts. A simple nomogram was developed to predict the postoperative SIRS in the training cohort using two logistic regression models and the brute force algorithm. The discriminative performance of this model was determined by area under the receiver operating characteristics curve (AUC). The external validity of the nomogram was assessed in the validation cohort.ResultsA total of 5,904 patients spanning from January 2015 to December 2019 were enrolled in the training cohort and 1,105 patients from January 2020 to September 2020 comprised the temporal validation cohort, in which incidence rates of postoperative SIRS were 24.6 and 20.2%, respectively. Six feature variables were identified as valuable predictors to construct the nomogram, with high AUCs (0.800 [0.787, 0.813] and 0.822 [0.790, 0.854]) and relatively balanced sensitivity (0.718 and 0.739) as well as specificity (0.718 and 0.729) in both training and validation cohorts. An online risk calculator was established for clinical application.ConclusionWe developed a patient-specific model that may assist in predicting postoperative SIRS among the aged patients

The application of dual clumped isotope thermometer (Δ47 and Δ48) to the understanding of dolomite formation

Although several studies have shown the possibility of kinetic isotopic effects during the precipitation of carbonates using the dual clumped isotope proxy (Δ47 and Δ48), this approach has not yet been applied to the study of dolomite. We present Δ47 and Δ48 values of two types of Cenozoic Bahamian dolomites formed by distinctly different mechanisms. One dolomite, present in a core drilled on the island of San Salvador, is believed to have formed from normal seawater in the open system, while the other, taken from the Clino core drilled on the margin of the Great Bahama Bank, was precipitated associated with microbial sulfate reduction in the closed system. The Δ48-derived temperatures of San Salvador dolomites are consistent with their Δ47-temperatures, which are in turn close to the expected value of normal seawater. In contrast, dolomites from Clino show slightly elevated Δ47-derived temperatures (∼15 °C higher than the expected) and significantly increased Δ48-temperatures (∼145 °C) that are positively correlated with the sulfur isotopes of carbonate associated sulfate, in excess of +30‰. Such an association suggests a non-equilibrium process driven by microbial sulfate reduction, which elevates the alkalinity and depresses the pH of dolomitizing fluids. Notably, the greater amplitude of disequilibrium in Δ48 relative to Δ47 values demonstrates the sensitivity of the Δ48 proxy to kinetic isotope effects in dolomite. Conclusively, this study shows the potential of the dual clumped isotope proxy to identify microbial-mediated dolomitization in modern and ancient records

Influence of frequency detuning on carrier-wave Rabi flop-related phenomena in the extreme nonlinear optics regime

In a simplified two-level atom or atomic-like system, resonantly interacting with laser, the so-called carrier-wave Rabi flop occurs accompanied by the occurrence of higher spectral components when the Rabi frequency is comparable with the exciting laser frequency [S. Hughes, Phys. Rev. Lett.81, 3363 (1998)]. Beyond resonance, the introduction of a small detuning does not play a negative role as expected, however, the spectral intensity versus detuning exhibits a Gaussian-like distribution pattern, i.e., there exists an optimal detuning value for the maximal spectral intensity. In addition, the propagation effect also shows an obvious influence, manifested as an obvious shift of this optimal detuning value

Clumped isotope acid fractionation factors for dolomite and calcite revisited: Should we care?

During the analysis of the Δ47 values of CO2 derived from carbonates, the acid fractionation factor not only allows Δ47 values produced from carbonates and reacted at different temperatures (usually 25 and 90 °C) to be compared to one another, but also provides an effective tool to better understand the mechanism and rate of isotopic exchange of oxygen with water during the phosphoric acid digestion of carbonate minerals. In this study, experiments have been conducted in which calcite (1 sample) and dolomite (4 samples), with varying Δ47 values, have been digested in phosphoric acid (H3PO4) at five different temperatures between 25 and 90 °C using both the common acid bath and sealed vessel methods. From these experiments, we show that calcite has an acid fractionation factor which is independent of the reaction method. In contrast, all four dolomites show significant differences between the two methods with the sealed vessel reactions showing much smaller acid fractionation factors than the common acid bath. The magnitude of the acid fractionation factor in the dolomites is also dependent upon the absolute Δ47 value of the sample, with samples possessing lower Δ47 values producing lower acid fractionation factors than those with higher Δ47 values. The explanation for the difference in the behavior of acid fractionation factors between calcite and dolomite, in regard to the technique used, is believed to be related to the rate of reaction of the two minerals and thus the time in which the CO2 is in contact with the acid and allowed to exchange with the H2O in the acid and produced during the reaction.•Four dolomite and one calcite were digested using common acid bath and sealed vessel methods.•Five reaction temperatures in these two experimental methods were conducted from 25 to 90 °C.•Insignificant differences in Δ47 values between CDES and I-CDES correcting frameworks.•All dolomites show a significant difference between two reaction methods.•The magnitude of acid fractionation factors in dolomite and calcite depends on absolute Δ47 values

FABRIC-SPECIFIC ISOTOPIC VARIABILITY IN LATE EDIACARAN DOLOMITES, SOUTH CHINA: ELUCIDATED BY MAGNESIUM, SULPHUR AND CLUMPED ISOTOPES

Dolomite (CaMg(CO (sub 3) )2) as a major carbonate mineral commonly distributes on the shallow-water platform throughout Earth history. Due to its thermodynamic stability, stoichiometric dolomite is less susceptible to the chemical alterations and often regarded as a reliable archive to reconstruct past environmental and ocean chemistry conditions. This is particularly important during the Precambrian time as it lacks of biological proxies. However, using dolomite as a geochemical proxy is challenging due to potential exposure to various diagenetic realms, such as burial or subaerial condition, which can partly alter and, in some cases, completely overprint the original signatures. Such phenomenon will generate large isotopic variations depending on the different dolomite fabrics. To examine the fidelity of geochemical records in dolomite and understand the governing processes of fabric-specific isotopic variations, the dolomite in the Dengying Formation of Ediacaran was selected as an example. Five fabrics (abiogenic and biogenic micrites, dolomitized ooids and early cement, and saddle dolomite) were identified in this Ediacaran-aged formation and they show a large variation in delta 13C values (from 0 to 6 ppm). Based on clumped isotopes (Delta 47) and strontium contents, this study calculated the degree of fluid-rock interaction (W/R ratio) and established a diagenetic framework for each fabric. Both the abiogenic and biogenic micrites were characterized by the rock-buffered system (low W/R ratio = 0.1-0.2), while the fabrics of the ooid, early cement and saddle dolomite were buffered by the hydrothermal fluids in the late diagenesis (high W/R = 1.4-5). Furthermore, this interpretation is further supported by high delta 26Mg values, Sr and Mn contents and elevated delta 34SCAS values in biogenic micrite indicating a closed or partly closed diagenetic system which allow the Rayleigh distillation enriching (super 26) Mg and enhanced (super 34) S of residual SO (sub 4) (super 2-) by bacterial sulphate reduction. In contrast, the fabrics (ooids, early cement and saddle dolomite) in the hydrothermal-buffered system showed an extremely low values indelta 34SCAS, which can be interpreted as a result of oxidation of sulphides (e.g. pyrite). The outcome of this study highlights the utility of systemically petrographic analysis and multiple geochemical proxies to decipher the diagenetic processes of dolomite and caution on interpreting the geochemical records in dolomite successions

Reconstructing paleoceanographic conditions during the middle Ediacaran: Evidence from giant ooids in South China

The Ediacaran was a period of intense environmental change in Earth history. Transient pulses of oxygenation and shifts in ocean chemistry have been interpreted from a range of geochemical proxies, including rare earth elements and yttrium (REY), but it is still a challenge to reconstruct paleoceanographic conditions due to the scarcity of reliable recorder. In this study, we explore the possibility that a newly-discovered deposit of giant ooids in the Nanshanping outcrop in South China contains a relatively intact record of the REE composition of Ediacaran seawater, providing an important window into the redox state of the surface ocean at this time. These ooids are relatively large in size (similar to 1-6 mm), and exhibit densely banded laminae. A regional chemostratigraphic correlation shows that the giant-ooid-bearing succession in South China is in the upper part of the second Ediacaran positive carbon isotopic shift (EP2), and thus its occurrence was not associated with the Shuram Excursion. Additionally, the occurrences of giant-ooid-bearing oolites in different blocks were not synchronous during the middle Ediacaran. In-situ laser ablation analysis of giant-ooid cortices reveals that the shale-normalized REY patterns are similar to those of modern seawater, including depleted light REEs, superchondritic Y/Ho ratios, and positive La anomalies. Yet, no Ce anomalies (1.0 +/- 0.15) in numerous ooid cortices seems to indicate a suboxidized condition of surface ocean in South China at that time. The petrographic and geochemical evidence support the weak diagenetic alteration of the pure giant ooids during burial. They formed in open-ocean settings with energetic hydrodynamic environments and were affected by early dolomitization that might preserve mostly original petrographic fabrics and REY signatures from further diagenetic overprinting. The characteristics of Ce anomalies and REY compositions acquired from the giant ooids indicate that the surface ocean was suboxidized in South China during the late stage of EP2, implying the very low atmospheric O-2 level at that time. Our results suggest that giant ooids may be a reliable analytical target that provide a snapshot into palaeoceanographic conditions during this crucial period of dynamic changes in early Earth history

Diagenetic fluid evolution of dolomite from the Lower Ordovician in Tazhong area, Tarim Basin:Clumped isotopic evidence

Based on the relationship between the relative abundance of 13C and 18O bonds and temperature, carbonate clumped isotope (Δ47) has the special characteristic of indicating temperature even in the absence of knowledge about the chemical and isotopic composition of the fluid from which the carbonates precipitated.This property hence makes the technique an excellent temperature proxy in the study of diagenetic fluids.As such, this study employs clumped isotopes to examine the origin of diagenetic fluids in deep and ultra-deep subsurface settings and we assess their impact on the development of reservoir quality.This study considers both the matrix and associated cements.Three episodes of diagenesis are revealed. In the first stage, the fluids formed in a shallow-to-medium burial environment and the matrix was altered to have a powder-crystal to finely-crystalline texture.The range of Δ47 derived temperatures ranges from 69 to 94℃, and the δ18Ow values are from +1.81‰ to +5.19‰ SMOW.These data suggest that the fluid is modified seawater.The second diagenetic episode was influence by a brine after the sequence was deeply-bured.Here, the matrix was altered to a me-dium-crystalline texture and the Δ47 derived temperatures range from 111 to 113℃, and the δ18Ow values range from +8.46‰ to +8.95‰ SMOW, indicating that a substantial water-rock interaction occurred.The third diagenetic episode was induced by hydrothermal fluids, likely travelling along faults and fractures, which yielded abundant saddle dolomite.Here, Δ47 derived temperatures varies from 130 to 147℃ and the δ18Ow values from +7.93‰ to +9.42‰ SMOW.The vug-and vein-filling carbonates have a wide range of δ18Ocarb and δ13Ccarb values.The δ18Ocarb values span -17.38‰ to -5.84‰ VPDB, and the δ13Ccarb values from 3.57‰ to -1.33‰ VPDB, indicating multiple stages of fluid modification.Both the cores and photomicrographs demonstrate excellent reservoir quality for the Lower Ordovician Tazhong dolomites

Clumped isotopes of paired dolomite and calcite constraining alteration histories of ancient carbonate successions

Clumped isotope thermometry is an effective tool which allows to understand the post-depositional alteration, including recrystallization and solid-state reordering, of carbonate rocks. However, as both processes are controlled by elevated temperatures, it is frequently a challenge to distinguish between the relative importance of these two processes in deeply buried carbonate successions (depth > 5000 m or formation temperature > 150°C). In this paper, we have established a clumped isotopic framework of paired dolomite and calcite in order to decipher the relative influence of solid-state reordering versus recrystallization and consequently offer an improved understanding of the mechanisms involved. The material studied was derived from two deeply buried successions (Jurassic-Ediacaran) drilled in the central Sichuan Basin of South China. The calcite and dolomite minerals from these cores were separated using buffered acetic acid, and based on a two-component mixing model, the carbon, oxygen and clumped isotopic (Δ47) compositions of the two endmembers were determined. Based on an evaluation of solid-state reordering models, we conclude that micritic carbonates (dolomite and calcite) from the Jurassic to the Cambrian have been altered during burial by the geothermal gradient as determined by vitrinite reflectance. The Ediacaran micritic dolomite records a hydrothermal event in the transition between the Ediacaran and Cambrian. In contrast, the clumped isotopic temperature of Ediacaran saddle dolomites reflects subsequent hydrothermal activity during the Silurian and Devonian and shows compositional variations controlled by cooling rates. This study highlights the utility of the theoretical framework based on paired dolomite and calcite records to untangle overprinted signals of clumped isotopes in ancient carbonate rocks and gives insight to better understand the complexity of alteration processes in deeply burial carbonate successions

Tracking hydrological processes during the formation of Marinoan cap dolostone; insight from reordered clumped isotopes

Widespread dolomite precipitates, known as cap dolostone, were deposited in the aftermath of the Neoproterozoic Marinoan glaciation, and are thought to reflect dramatic perturbations of seawater chemistry in the aftermath of the glaciation. However, controversy still remains on the nature and the hydrodynamic process of fluids that produced these dolomites. In this study, we present clumped isotope values (Delta (sub 47) ) of Neoproterozoic Marinoan cap carbonates from five sections in Namibia and South China and examine the spatial variation of the post-glacial hydrodynamics across the two carbonate platforms. The Delta (sub 47) -temperatures show the mineral-specific variation in dolostone and limestone, a feature that can be attributed to the solid-state reordering driven by short-term hydrothermal events. Based on the results of theoretical calculations and laboratory experiments, we present a framework that enables the utilization of the reordered clumped isotopes to trace the dolomitization process. Under such a framework, we find the reordering patterns determined by clumped isotopes are indistinguishable from the inner to outer platforms as well as between the dolostone and limestone, which suggests the mixture of meltwater and seawater as the source of dolomitizing fluids. Our findings demonstrate the clumped isotope can be used to trace hydrological processes for deep-time successions, and offer insight into the enigmatic origin of cap carbonates