88 research outputs found
A Mechanistic Study of Atlantic Meridional Overturning Circulation Changes on Tropical Atlantic Climate
An eddy-permitting 2-1/2-layer Reduced Gravity Ocean (RGO) model is
developed. Compared with the conventional 2-1/2-layer RGO models, the new model
has improvements in subsurface thermodynamics, vertical mixing scheme and open
boundary conditions. Using this new 2-1/2-layer RGO model as a dynamical tool, a
systematic investigation of the role of oceanic processes in controlling tropical Atlantic
sea-surface temperature (SST) response to Atlantic Meridional Overturning Circulation
(AMOC) changes is carried out by varying the strength of northward mass transport at
the open boundaries. It is found that the North Brazil Undercurrent (NBUC) reverses its
direction in response to a shut-down of the AMOC. Such circulation change allows
warm waters of the northern subtropical gyre enter the equatorial zone, giving rise to a
prominent warming in the Gulf of Guinea and off the coast of Africa. Sensitivity
experiments further show that the SST response behaves nonlinearly to AMOC changes.
The rate of SST changes increases dramatically when the AMOC strength is below a
threshold value. This nonlinear threshold behavior depends on the position of
subsurface temperature gradient. The new RGO is coupled to an atmosphere general
circulation model (AGCM) (CCM3.6). The coupled model is capable of capturing major
features of tropical Atlantic variability. With the aid of this coupled model, a series of
experiments with different combinations of oceanic and atmospheric processes are
carried out to elucidate the relative importance of the oceanic processes and atmospheric
processes in AMOC-induced tropical Atlantic variability/change. It is found that the oceanic processes are a primary factor contributing to the warming at and south of the
equator and the precipitation increase over the Gulf of Guinea, while atmospheric
processes are responsible for the surface cooling of the tropical north Atlantic and
southward displacement of ITCZ. The sensitivity of the coupled system to different
strength of the AMOC is further investigated. It is found that equatorial SST and
precipitation response also behaves nonlinearly to AMOC changes. The impact of
AMOC changes on Tropical Instability Waves (TIWs) is assessed. It is found that the
activity of TIWs is reduced in response to the AMOC-induced equatorial SST warming.
Correlation analysis suggests that AMOC may affect TIW activities by modifying SST
gradient north of the equator
How do uncertainties in NCEP R2 and CFSR surface fluxes impact tropical ocean simulations?
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 Climate Dynamics 49 (2017): 3327–3344, doi:10.1007/s00382-016-3516-6.NCEP/DOE reanalysis (R2) and Climate Forecast System Reanalysis (CFSR) surface fluxes are widely used by the research community to understand surface flux climate variability, and to drive ocean models as surface forcings. However, large discrepancies exist between these two products, including (1) stronger trade winds in CFSR than in R2 over the tropical Pacific prior 2000; (2) excessive net surface heat fluxes into ocean in CFSR than in R2 with an increase in difference after 2000. The goals of this study are to examine the sensitivity of ocean simulations to discrepancies between CFSR and R2 surface fluxes, and to assess the fidelity of the two products. A set of experiments, where an ocean model was driven by a combination of surface flux component from R2 and CFSR, were carried out. The model simulations were contrasted to identify sensitivity to different component of the surface fluxes in R2 and CFSR. The accuracy of the model simulations was validated against the tropical moorings data, altimetry SSH and SST reanalysis products.
Sensitivity of ocean simulations showed that temperature bias difference in the upper 100m is mostly sensitive to the differences in surface heat fluxes, while depth of 20°C (D20) bias difference is mainly determined by the discrepancies in momentum fluxes. D20 simulations with CFSR winds agree with observation well in the western equatorial Pacific prior 2000, but have large negative bias similar to those with R2 winds after 2000, partly because easterly winds over the central Pacific were underestimated in both CFSR and R2. On the other hand, the observed temperature variability is well reproduced in the tropical Pacific by simulations with both R2 and CFSR fluxes. Relative to the R2 fluxes, the CFSR fluxes improve simulation of interannual variability in all three tropical oceans to a varying degree. The improvement in the tropical Atlantic is most significant and is largely attributed to differences in surface winds
Reproductive Outcomes of In Vitro Fertilization and Fresh Embryo Transfer in Infertile Women With Adenomyosis: A Retrospective Cohort Study
BackgroundAdenomyosis is commonly encountered in infertile women; however, it is still unclear whether adenomyosis has a detrimental effect on in vitro fertilization and embryo transfer (IVF-ET) outcomes.MethodWe enrolled 1146 patients with adenomyosis and 1146 frequency-matched control women in a 1:1 ratio based on age, BMI, and basal follicle-stimulating hormone (FSH) level. After controlling for other factors, the rates of clinical pregnancy, miscarriage, live birth, and obstetric complications were compared between two groups.ResultsThere was no significant difference in clinical pregnancy rate between the two groups (38.1% vs. 41.6%; P=0.088). The implantation rate (25.6% versus 28.6%, P=0.027) and live birth rate (26% versus 31.5%, P=0.004) were significantly lower in the women with adenomyosis than in the controls. The miscarriage rate in the adenomyosis group was higher than that in the control group (29.1% versus 17.2%, P=0.001). After adjusting for confounding factors, multivariate analysis showed the clinical pregnancy rate was not statistically different between the two groups (OR: 0.852, P=0.070). In the adenomyosis group, the rate of miscarriage(OR: 1.877, P=0.000), placenta previa (OR: 2.996, P=0.042)and preeclampsia (OR: 2.287, P=0.042)were increased significantly, while live birth rate (OR: 0.541, P=0.000) was reduced significantly than control group.ConclusionAdenomyosis has negative effect on IVF-ET outcomes in which miscarriage risk increased, live birth rate reduced and obstetric complications increased
The global ocean water cycle in atmospheric reanalysis, satellite, and ocean salinity
This study provides an assessment of the uncertainty in ocean-surface (OS) freshwater budgets and variability using evaporation (E) and precipitation (P) from 10 atmospheric reanalyses, 2 combined satellite-based E-P products, and 2 observation-based salinity products. Three issues are examined: the uncertainty level in the OS freshwater budget in atmospheric reanalyses, the uncertainty structure and association with the global ocean wet/dry zones, and the potential of salinity in ascribing the uncertainty in E-P. The products agree on the global mean pattern but differ considerably in magnitude. The OS freshwater budgets are 129±10 (8%) cm yr-1 for E, 118±11 (9%) cm yr-1 for P, and 11±4 (36%) cm yr-1 for E-P, where the mean and error represent the ensemble mean and one standard deviation of the ensemble spread. The E-P uncertainty exceeds the uncertainty in E and P by a factor of four or more. The large uncertainty is attributed to P in the tropical wet zone. Most reanalyses tend to produce a wider tropical rain band when compared to satellite products, with the exception of two recent reanalyses that implement an observation-based correction for the model-generated P over land. The disparity in the width and the extent of seasonal migrations of the tropical wet zone causes large spread in P, implying that the tropical moist physics and the realism of tropical rainfall remain a key challenge. Satellite salinity appears feasible to evaluate the fidelity of E-P variability in three tropical areas, where the uncertainty diagnosis has a global indication
Prenatal diagnosis and clinical management of cardiac rhabdomyoma: a single-center study
ObjectiveThe study aims to assess the ultrasonic features of fetal cardiac rhabdomyoma (CR), track the perinatal outcome and postnatal disease progression, investigate the clinical utility of ultrasound, MRI and tuberous sclerosis complex (TSC) gene analysis in CR evaluation, and offer evidence for determing of fetal CR prognosis.MethodsWe conducted a retrospective analysis of prenatal ultrasound-diagnosed fetal CR cases in our hospital from June 2011 to June 2022, tracked the perinatal outcomes, regularly followed live infants to analyze cardiac lesion changes and disease progression, and compared the sensitivities of ultrasound, MRI and their combination in the detecting of intracranial sclerosing nodules.ResultsOur study included 54 fetuses with CR: 32 pregnancies were terminated, 22 were delivered, 35 were diagnosed with TSC, 13 had simple CR without TSC, and in 6 cases, remained unclear whether TSC accompanied the CR due to insufficient evidence. 45 fetuses (83.3%) had multiple lesions, while 9 fetuses (16.7%) presented with a single lesion. Twelve cases had intracardiac complications, all associated with multiple lesions, and these cases exhibited larger maximum tumor diameters than the non-complicated group. Multiple intracardiac lesions were more prevalent in the TSC group than in the simple CR group. However, there was no significant difference in maximum tumor diameter between the two groups. Among 30 fetuses who underwent fetal brain MRI, 23 were eventually diagnosed with TSC, with 11 fetuses showing intracranial sclerosis nodules by ultrasound and 15 by MRI, and the diagnostic consistency was moderate (k = 0.60). Twenty-two fetuses were born and followed up for 6–36 months. CR lesions diminished or disappeared in 18 infants (81.8%), while they remained unchanged in 4 infants (18.2%). Ten out of 12 (83.3%) surviving children diagnosed with TSC developed epilepsy, and 7 (58.3%) had neurodevelopmental dysfunction.ConclusionsThe majority of CR cases involve multiple lesions, which are a primary risk factor for TSC. Through prenatal ultrasound examination is crucial for assessing fetal CR prognosis. Although ultrasound combined with MRI can detect intracranial sclerosis nodules in TSC fetuses, its sensitivity is limited. TSC gene sequencing is an essential diagnostic method. Simple CR cases without TSC generally have a favorable prognosis
Integrated Bioinformatic Analysis of a Competing Endogenous RNA Network Reveals a Prognostic Signature in Endometrial Cancer
In endometrial carcinoma, the clinical outcome directly correlates with the TNM stage, but the lack of sufficient information prevents accurate prediction. The molecular mechanism underlying the competing endogenous RNA (ceRNA) hypothesis has not been investigated in endometrial cancer. Multi-bioinformatic analyses, including differentially expressed gene analysis, ceRNA network construction, Cox regression analysis, function enrichment analysis, and protein-protein network analysis, were performed on the sequence data acquired from The Cancer Genome Atlas (TCGA) data bank. A ceRNA network comprising 366 mRNAs, 27 microRNAs (miRNAs), and 66 long non-coding RNAs (lncRNAs) was established. Survival analysis performed with the univariate Cox regression analysis revealed nine lncRNAs with prognostic power in endometrial carcinoma. In multivariate Cox regression analysis, a signature comprising LINC00491, LINC00483, ADARB2-AS1, and C8orf49 showed remarkable prognostic power. Risk score and neoplasm status, but not TNM stage, were independent prognostic factors of endometrial carcinoma. A ceRNA network comprising differentially expressed mRNAs, miRNAs, and lncRNAs may reveal the molecular events involved in the progression of endometrial carcinoma. In addition, the signature with prognostic value may discriminate patients with increased risk for poor outcome, which may allow physicians to take accurate decisions
PSR J1926-0652: A Pulsar with Interesting Emission Properties Discovered at FAST
We describe PSR J1926-0652, a pulsar recently discovered with the
Five-hundred-meter Aperture Spherical radio Telescope (FAST). Using sensitive
single-pulse detections from FAST and long-term timing observations from the
Parkes 64-m radio telescope, we probed phenomena on both long and short time
scales. The FAST observations covered a wide frequency range from 270 to 800
MHz, enabling individual pulses to be studied in detail. The pulsar exhibits at
least four profile components, short-term nulling lasting from 4 to 450 pulses,
complex subpulse drifting behaviours and intermittency on scales of tens of
minutes. While the average band spacing P3 is relatively constant across
different bursts and components, significant variations in the separation of
adjacent bands are seen, especially near the beginning and end of a burst. Band
shapes and slopes are quite variable, especially for the trailing components
and for the shorter bursts. We show that for each burst the last detectable
pulse prior to emission ceasing has different properties compared to other
pulses. These complexities pose challenges for the classic carousel-type
models.Comment: 13pages with 12 figure
The Prevalence of Immunologic Injury in Renal Allograft Recipients with De Novo Proteinuria
Post-transplant proteinuria is a common complication after renal transplantation; it is associated with reduced graft and recipient survival. However, the prevalence of histological causes has been reported with considerable variation. A clinico-pathological re-evaluation of post-transplant proteinuria is necessary, especially after dismissal of the term “chronic allograft nephropathy,” which had been considered to be an important cause of proteinuria. Moreover, urinary protein can promote interstitial inflammation in native kidney, whether this occurs in renal allograft remains unknown. Factors that affect the graft outcome in patients with proteinuria also remain unclear. Here we collected 98 cases of renal allograft recipients who developed proteinuria after transplant, histological features were characterized using Banff scoring system. Cox proportional hazard regression models were used for graft survival predictors. We found that transplant glomerulopathy was the leading (40.8%) cause of post-transplant proteinuria. Immunological causes, including transplant glomerulopathy, acute rejection, and chronic rejection accounted for the majority of all pathological causes of proteinuria. Nevertheless, almost all patients that developed proteinuria had immunological lesions in the graft, especially for interstitial inflammation. Intraglomerular C3 deposition was unexpectedly correlated with the severity of proteinuria. Moreover, the severity of interstitial inflammation was an independent risk factor for graft loss, while high level of hemoglobin was a protective factor for graft survival. This study revealed a predominance of immunological parameters in renal allografts with post-transplant proteinuria. These parameters not only correlate with the severity of proteinuria, but also with the outcome of the graft
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Global Oceans, BAMS State of the Climate in 2021, Chapter 3
Patterns of variability in ocean properties are often closely related to large-scale climate pattern indices, and 2021 is no exception. The year 2021 started and ended with La Niña conditions, charmingly dubbed a “double-dip” La Niña. Hence, stronger-than-normal easterly trade winds
in the tropical south Pacific drove westward surface current anomalies in the equatorial Pacific; reduced sea surface temperature (SST) and upper ocean heat content in the eastern tropical Pacific; increased sea level, upper ocean heat content, and salinity in the western tropical Pacific;
resulted in a rim of anomalously high chlorophyll-a (Chla) on the poleward and westward edges of the anomalously cold SST wedge in the eastern equatorial Pacific; and increased precipitation over the Maritime Continent.
The Pacific decadal oscillation remained strongly in a negative phase in 2021, with negative SST and upper ocean heat content anomalies around the eastern and equatorial edges of the North Pacific and positive anomalies in the center associated with low Chla anomalies. The South
Pacific exhibited similar patterns. Fresh anomalies in the northeastern Pacific shifted towards the west coast of North America.
The Indian Ocean dipole (IOD) was weakly negative in 2021, with small positive SST anomalies in the east and nearly-average anomalies in the west. Nonetheless, upper ocean heat content was anomalously high in the west and lower in the east, with anomalously high freshwater flux and low sea surface salinities (SSS) in the east, and the opposite pattern in the west, as might be expected during a negative phase of that climate index.
In the Atlantic, the only substantial cold anomaly in SST and upper ocean heat content persisted east of Greenland in 2021, where SSS was also low, all despite the weak winds and strong surface heat flux anomalies into the ocean expected during a negative phase of the North Atlantic
Oscillation. These anomalies held throughout much of 2021. An Atlantic and Benguela Niño were both evident, with above-average SST anomalies in the eastern equatorial Atlantic and the west coast of southern Africa. Over much of the rest of the Atlantic, SSTs, upper ocean heat content, and sea level anomalies were above average.
Anthropogenic climate change involves long-term trends, as this year’s chapter sidebars emphasize. The sidebars relate some of the latest IPCC ocean-related assessments (including carbon, the section on which is taking a hiatus from our report this year). This chapter estimates that SST increased at a rate of 0.16–0.19°C decade−1 from 2000 to 2021, 0–2000-m ocean heat content warmed by 0.57–0.73 W m−2 (applied over Earth’s surface area) from 1993 to 2021, and global
mean sea level increased at a rate of 3.4 ± 0.4 mm yr−1 from 1993 to 2021. Global mean SST, which is more subject to interannual variations than ocean heat content and sea level, with values typically reduced during La Niña, was ~0.1°C lower in 2021 than in 2020. However, from 2020 to
2021, annual average ocean heat content from 0 to 2000 dbar increased at a rate of ~0.95 W m−2, and global sea level increased by ~4.9 mm. Both were the highest on record in 2021, and with year-on-year increases substantially exceeding their trend rates of recent decades
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