Uncovering the spatial heterogeneity of Ediacaran carbon cycling

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Geobiology 15 (2017): 211–224, doi:10.1111/gbi.12222.Records of the Ediacaran carbon cycle (635 to 541 million years ago) include the Shuram excursion (SE), the largest negative carbonate-carbon isotope excursion in Earth history (down to -12 ‰). The nature of this excursion remains enigmatic given the difficulties of interpreting a perceived extreme global decrease in the δ13C of seawater dissolved inorganic carbon (DIC). Here, we present carbonate and organic carbon isotope (δ13Ccarb and δ13Corg) records from the Ediacaran Doushantuo Formation along a proximal-to-distal transect across the Yangtze Platform of South China as a test of the spatial variation of the SE. Contrary to expectations, our results show that the magnitude and morphology of this excursion and its relationship with coexisting δ13Corg are highly heterogeneous across the platform. Integrated geochemical, mineralogical, petrographic, and stratigraphic evidence indicates that the SE is a primary marine signature. Data compilations demonstrate that the SE was also accompanied globally by parallel negative shifts of δ34S of carbonate-associated sulfate (CAS) and increased 87Sr/86Sr ratio and coastal CAS concentration, suggesting elevated continental weathering and coastal marine sulfate concentration during the SE. In light of these observations, we propose a heterogeneous oxidation model to explain the high spatial heterogeneity of the SE and coexisting δ13Corg records of the Doushantuo, with likely relevance to the SE in other regions. In this model, we infer continued marine redox stratification through the SE but with increased availability of oxidants (e.g., O2 and sulfate) limited to marginal near-surface marine environments. Oxidation of limited spatiotemporal extent provides a mechanism to drive heterogeneous oxidation of subsurface reduced carbon mostly in shelf areas. Regardless of the mechanism driving the SE, future models must consider the evidence for spatial heterogeneity in δ13C presented in this study.We thank the National Key Basic Research Program of China (Grant 2013CB955704) and the State Key R&D project of China (Grant 2016YFA060104) as well as the NSF-ELT program and the NASA Astrobiology Institute (TWL) for funding

Gender Difference in 2-Year Mortality and Immunological Response to ART in an HIV-Infected Chinese Population, 2006–2008

Since it was initiated in 2002, the China Free Antiretroviral Treatment (ART) Program has been progressing from an emergency response to a standardized treatment and care system. As of December 31, 2009, a total of 81,880 patients in 31 provinces, autonomous regions, and special municipalities received free ART. Gender differences, however, in mortality and immunological response to ART in this cohort have never been described.To understand whether women and men who enrolled in the China National Free ART Program responded equally well to the treatment.A retrospective analysis of the national free ART databases from June 2006-December 2008 was performed. HIV-infected subjects who were 18 years or older, ART naïve at baseline, and on a 3TC regimen enrolled in the program from June 1 to December 31, 2006, were included in this study, then followed up to 2 years.Among 3457 enrolled subjects who met the inclusion criteria, 59.2% were male and 40.8% female. The majority of the subjects were 19-44 years old (77%) and married (72%). Over the full 24 months of follow-up, the mortality rate was 19.0% in males and 11.4% in females (p = 0.0014). Males on therapy for 3-24 months were more likely to die than females (HR = 1.46, 95% CI: 1.04-2.06, p = 0.0307) after adjusting for baseline characteristics. Compared to men, women had higher CD4+ counts over time after initiating ART (p<0.0001).Our study showed that women had an overall lower mortality and higher CD4+ counts than men in response to ART treatment, which may be attributed to adherence, biological factors, social, cultural and economic reasons. Further study is needed to explore these factors that might contribute to the gender differences in mortality and immunological response to ART

The Effect of Plasma Triglyceride-Lowering Therapy on the Evolution of Organ Function in Early Hypertriglyceridemia-Induced Acute Pancreatitis Patients With Worrisome Features (PERFORM Study): Rationale and Design of a Multicenter, Prospective, Observational, Cohort Study

Background: Acute pancreatitis (AP) is a potentially life-threatening inflammatory disease with multiple etiologies. The prevalence of hypertriglyceridemia-induced acute pancreatitis (HTG-AP) has been increasing in recent years. It is reported that early triglyceride (TG) levels were associated with the severity of the disease, and TG- lowering therapies, including medical treatment and blood purification, may impact the clinical outcomes. However, there is no consensus regarding the optimal TG-lowering therapy, and clinical practice varies greatly among different centers. Our objective is to evaluate the TG-lowering effects of different therapies and their impact on clinical outcomes in HTG-AP patients with worrisome features. Methods: This is a multicenter, observational, prospective cohort study. A total of approximately 300 patients with HTG-AP with worrisome features are planned to be enrolled. The primary objective of the study is to evaluate the relationship between TG decline and the evolution of organ failure, and patients will be dichotomized depending on the rate of TG decline. The primary outcome is organ failure (OF) free days to 14 days after enrollment. Secondary outcomes include new-onset organ failure, new-onset multiple-organ failure (MOF), new-onset persistent organ failure (POF), new receipt of organ support, requirement of ICU admission, ICU free days to day 14, hospital free days to day 14, 60-day mortality, AP severity grade (Based on the Revised Atlanta Classification), and incidence of systemic and local complications. Generalized linear model (GLM), Fine and Gray competing risk regression, and propensity score matching will be used for statistical analysis. Discussion: Results of this study will reveal the current practice of TG-lowering therapy in HTG-AP and provide necessary data for future trials

Nanostructured electrochromic and photoelectrochemical materials and devices

Nanostructured tungsten oxide (WO3) and hydrated tungsten oxide (WO3•H2O) films were assembled on fluorine doped tin oxide (FTO) coated glass substrates by seed-assisted hydrothermal methods. Plate-like, brick-like and stick-like nanostructured WO3 or hydrated WO3 films were obtained by using sodium sulfate (Na2SO4), ammonium sulfate ((NH4)2SO4) and ammonium acetate (CH3COONH4)as capping agents, respectively.The electrochromic (EC) characteristics of the as-prepared films were investigated in single EC layer devices and complementary EC devices with Prussian blue (PB) as the counter electrode. Compared to the films without capping agent, the plate-like nanostructured 3WO3•H2O film grown with Na2SO4 shows significantly improved EC performance. A high coloration efficiency value of 112.7 cm2C-1 at 632.8 nm is obtained, and the response time for 90% transmittance changes is found to be 4.3 sfor coloration and 1.4 s for bleaching for a sample size ~2 cm2 (FTO sheet resistance:15Ω/□), respectively, while the brick-like monoclinic WO3 film displays a comparable switching response of tc,90%= 272 s and tb, 90%= 364 s (sample size ~2 cm2, FTO sheet resistance: 15Ω/□)and a coloration efficiency of 38.2 cm2C-1 at 632.8 nm. Both films show adjustable transmittance modulation under different voltages and a good reversible coloration/bleaching stability. The single layer EC devices based on these films demonstrate promising applications in smart windows and large-area information displays. Complementary EC devices based on nanostick/nanoparticle and nanobrick 3WO3•H2O film and PB film were also fabricated. The orthorhombic nanostick/nanoparticle 3WO3•H2O film grown with CH3COONH4 as the capping agent shows better EC performances than the nanobrick film without capping agent. A complementary EC device based on the nanostick/nanoparticle 3WO3•H2Ofilm and PB was assembled and shows higher optical modulation (54% at 754 nm), a larger coloration efficiency (151.9 cm2C-1 at 754 nm)and faster switching responses with a bleaching time of 5.7 sand a coloring time of 1.3 s (sample size ~2 cm2, FTO sheet resistance: 15Ω/□) than a single 3WO3•H2O layer device. Orthorhombic nanobrick 3WO3•H2O films were obtained by using (NH4)2SO4 as the capping agent, and a complementary device made up of the nanobrick 3WO3•H2O film and PB film was also fabricated and demonstrate smuch faster coloration/bleaching response (tc,90%= 1.8 s, tb,90%= 3.7 s for a sample size ~1.7cm2, FTO sheet resistance: 15Ω/□), larger coloration efficiency value (164.6 cm2C-1 at 632.8 nm) and increased color contrast. Moreover, a fast-switching negative photoelectrochromic (PEC) cell composed of dye-sensitized nanocrystalline TiO2 and PB electrodes was fabricated. Adjustable grayscales were obtained by illuminating the cell with different light intensity and time. The photo bleaching response of the cell at 100 mWcm-2 is 6.2 s, and the EC response with a 2 V bias is about 600 ms for 70% transmittance change at 780 nm with coloration efficiency of 103.4 cm2C-1 (sample size ~1.5 cm2, FTO sheet resistance: 15Ω/□). This hybrid PEC cell shows good stability and can be potentially applied in erasable displays. The photoelectrochemical(PE) properties of the porous WO3 thin films consisted of sheet-like, wedge-like and plate-like nanostructures with the capping agents of CH3COONH4, (NH4)2SO4 and Na2SO4 were also investigated. The sheet-like film grown using CH3COONH4 could generate anodic photocurrents of 1.15mA cm-2 for oxidization of methanol and 0.5 mA cm-2 for water splitting, the highest photoconversion efficiency of about 0.3% can be obtained for water splitting under simulated solar illumination. In summary, this dissertation addresses the fabrication and characterization of WO3or 3WO3•H2O films grown with various capping agents using the hydrothermal methods. Single layer EC devices and complementary layer EC devices based on these films were assembled and their EC performances were investigated. The photoelectrochemical properties of the porous WO3filmswere also studied. And a PEC cell based on PB electrodes was fabricated and investigated. The work done demonstrates the promising applications of the nanostructured WO3 or 3WO3•H2O films and PB films in EC and photoelectrochemical devices.DOCTOR OF PHILOSOPHY (EEE

Kuhn-Munkres parallel genetic algorithm for the set cover problem and its application to large-scale wireless sensor networks

Operating mode scheduling is crucial for the lifetime of wireless sensor networks. However, the growing scale of networks has made such a scheduling problem more and more challenging, as existing set cover and evolutionary algorithms become unable to provide satisfactory efficiency due to the curse of dimensionality. In this paper, a Kuhn-Munkres parallel genetic algorithm is developed to solve the set cover problem and is applied to lifetime maximization of large-scale wireless sensor networks. The proposed algorithm schedules the sensors into a number of disjoint complete cover sets and activates them in batch for energy conservation. It uses a divide-and-conquer strategy of dimensionality reduction, and the polynomial Kuhn-Munkres algorithm are hence adopted to splice the feasible solutions obtained in each subarea to enhance the search efficiency substantially. To further improve global efficiency, a redundant-trend sensor schedule strategy is developed. Additionally, we meliorate the evaluation function through penalizing incomplete cover sets, which speeds up convergence. Eight types of experiments are conducted on a distributed platform to test and inform the effectiveness of the proposed algorithm. The results show that it offers promising performance in terms of the convergence rate, solution quality, and success rate