837 research outputs found
Geochemical characteristics and mantle sources of the Oligo-Miocene primitive basalts from Sardinia: The role of subduction components.
During the Oligo-Miocene, the Island of Sardinia was covered by the products of voluminous magmatic activity, with a typical subduction-related signature. The mafic rocks of the Montresta (north) and Arcuentu (south) volcanic districts include primitive high MgO basalts whose trace element and Sr-, Nd- and Pb-isotope compositions constrain the nature and role of subduction-related components in the Tertiary Sardinian volcanism. The geochemical and isotopic data require an approximate degree of partial melting of 15% of a MORB-like depleted mantle prior to enrichment, and the input of two subduction components in the mantle wedge consisting of fluids from subducted oceanic crust (altered MORB) and fluids from subducted sediments. Ratios among trace elements which are variably compatible with fluid and melt phases (i.e. Th/Pb, Th/Nd and Sr/Nd) exclude the contribution of melts from the subducted slab. Models based on isotopic ratios indicate that the pre-subduction depleted mantle source of Sardinia magmas was enriched by 0.1-0.5% MORB fluid and less than 0.1% sediment fluid. The geochemical and isotopic compositions of the Montresta volcanic rocks are homogeneous, whereas those of the Arcuentu show quite heterogeneous characters, suggesting variations in mantle source over the long time-span (about 13 Ma) of volcanic activity in this district
Fetal brain hemodynamics in pregnancies at term: correlation with gestational age, birthweight and clinical outcome
Introduction: The primary aim of this study was to ascertain the strength of association between cerebral blood flow assessed in anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries and the following clinical outcomes: small for gestational age (SGA), induction of labor (IOL) for oligohydramnios and caesarean section (CS) for nonreassuring fetal status (NRFS) during labor. Material and methods: Retrospective analysis of prospectively collected data on consecutive singleton pregnancies from 40 0/7 to 41 6/7 week of gestation. UA, ACA, MCA, PCA pulsatility index (PI) were measured from 40 weeks of gestations. Furthermore, the ratios between cerebral blood flow and UA (CPR, ACA/UA and PCA/UA) were calculated and correlated with the observed outcomes. Results: Two hundred twenty-four singleton pregnancies were included in the study. Mean PI of either ACA (pâ=â.04), MCA (pâ=â.008), and PCA (pâ=â.003) were lower in the SGA compared to non-SGA group; furthermore, mean PCA PI was significantly lower than MCA PI (pâ=â.04). Furthermore, CPR (pâ=â.016), ACA/UA (pâ=â.02), and PCA/UA (pâ=â.003) were significantly lower in the SGA group compared to controls. UA, ACA, MCA, and PCA PI were higher in women undergoing IOL for oligohydramnios compared to controls. Logistic regression analysis showed that CPR and PCA/UA ratio were independently associated with SGA. SGA, ACA PI, and ACA/UA were independently associated with CS for NRFS. Finally, birthweight centile, were independently associated with IOL oligohydramnios. Despite this, the predictive accuracy of Doppler in detecting any of the explored outcome was only poor to moderate. Conclusion: Redistribution of cerebral blood flow at term is significantly associated with SGA, IOL for oligohydramnios and CS for NRFS in labor. However, the predictive accuracy of Doppler at term is only poor to moderate, thus advising against its use in clinical practice as a standalone screening test for adverse perinatal outcome in pregnancies at term. Key Message Redistribution of cerebral blood flow at term is significantly associated with SGA, IOL for oligohydramnios and CS for NRFS in labor
Sexual Intercourse for Induction of Spontaneous Onset of Labor: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
INTRODUCTION:
Sexual intercourse during pregnancy is commonly believed to trigger the onset of contractions and, therefore, labor. However, in low-risk pregnancies, there is neither association with preterm birth, premature rupture of membranes, or low birth weight, nor with spontaneous onset of labor at term.
AIM:
To evaluate the effectiveness of sexual intercourse for spontaneous onset of labor at term in singleton pregnancies.
METHODS:
The systematic search was conducted using electronic databases from inception of each database to June 2019. Review of articles also included the abstracts of all references retrieved from the search. Inclusion criteria were randomized controlled trials comparing sexual intercourse in singleton low-risk pregnancies at term with controls (either reduced number of coitus or no coitus) for spontaneous onset of labor. Estimates were pooled using random-effects meta-analysis.
MAIN OUTCOME MEASURES:
The primary outcome was the incidence of spontaneous onset of labor. The summary measures were reported as summary relative risk with 95% CI using the random-effects model of DerSimonian and Laird.
RESULTS:
Data extracted from 3 trials, including 1,483 women with singleton pregnancy at term and cephalic presentation, were analyzed. Women who were randomized in the sexual intercourse group had similar incidence of spontaneous onset of labor compared with control subjects (0.82% vs 0.80%; relative risk 1.02, 95% CI 0.98-1.07).
CLINICAL IMPLICATION:
Sexual intercourse should not be restricted in low-risk term pregnancies. Further studies are needed to properly evaluate the impact of orgasm, penetration, condom use, frequency of intercourse and other factors on induction of labor at term.
STRENGTH & LIMITATIONS:
Our study has several strengths. The three included trials had low risk of allocation bias; intention-to-treat analysis was used; this is the first meta-analysis on this issue so far. Limitations mainly depend on the design of the included studies. Firstly, compliance to the protocol relied on self-reporting by patients; in addition, not all the features of sexual intercourse could be adequately assessed (orgasm, nipple stimulation, sexual positions, etc.).
CONCLUSION:
In women with singleton, cephalic, low-risk pregnancies, sexual intercourse at term does not significantly increase the incidence of spontaneous onset of labor
White matter tract disconnection in Gerstmann's syndrome: Insights from a single case study
It has been suggested that Gerstmann's syndrome is the result of subcortical disconnection rather than emerging from damage of a multifunctional brain region within the parietal lobe. However, patterns of white matter tract disconnection following parietal damage have been barely investigated. This single case study allows characterising Gerstmann's syndrome in terms of disconnected networks. We report the case of a left parietal patient affected by Gerstmann's tetrad: agraphia, acalculia, left/right orientation problems, and finger agnosia. Lesion mapping, atlas-based estimation of probability of disconnection, and DTI-based tractography revealed that the lesion was mainly located in the superior parietal lobule, and it caused disruption of both intraparietal tracts passing through the inferior parietal lobule (e.g., tracts connecting the angular, supramarginal, postcentral gyri, and the superior parietal lobule) and fronto-parietal long tracts (e.g., the superior longitudinal fasciculus). The lesion site appears to be located more superiorly as compared to the cerebral regions shown active by other studies during tasks impaired in the syndrome, and it reached the subcortical area potentially critical in the emergence of the syndrome, as hypothesised in previous studies. Importantly, the reconstruction of tracts connecting regions within the parietal lobe indicates that this critical subcortical area is mainly crossed by white matter tracts connecting the angular gyrus and the superior parietal lobule. Taken together, these findings suggest that this case study might be considered as empirical evidence of Gerstmann's tetrad caused by disconnection of intraparietal white matter tracts
Initial operation of the International Gravitational Event Collaboration
The International Gravitational Event Collaboration, IGEC, is a coordinated
effort by research groups operating gravitational wave detectors working
towards the detection of millisecond bursts of gravitational waves. Here we
report on the current IGEC resonant bar observatory, its data analysis
procedures, the main properties of the first exchanged data set. Even though
the available data set is not complete, in the years 1997 and 1998 up to four
detectors were operating simultaneously. Preliminary results are mentioned.Comment: 8 pages, 2 figures, 3 tables; Proceeding of the GWDAW'99. Submitted
to the International Journal of Modern Physic
All-sky search of NAUTILUS data
A search for periodic gravitational-wave signals from isolated neutron stars
in the NAUTILUS detector data is presented. We have analyzed half a year of
data over the frequency band Hz/s and over the entire sky. We have divided the
data into 2 day stretches and we have analyzed each stretch coherently using
matched filtering. We have imposed a low threshold for the optimal detection
statistic to obtain a set of candidates that are further examined for
coincidences among various data stretches. For some candidates we have also
investigated the change of the signal-to-noise ratio when we increase the
observation time from two to four days. Our analysis has not revealed any
gravitational-wave signals. Therefore we have imposed upper limits on the
dimensionless gravitational-wave amplitude over the parameter space that we
have searched. Depending on frequency, our upper limit ranges from to . We have attempted a statistical
verification of the hypotheses leading to our conclusions. We estimate that our
upper limit is accurate to within 18%.Comment: LaTeX, 12 page
Outcome of twinâtwin transfusion syndrome according to Quintero stage of disease: systematic review and metaâanalysis
Objectives
To report the outcome of pregnancies complicated by twinâtwin transfusion syndrome (TTTS) according to Quintero stage.
Methods
MEDLINE, EMBASE and CINAHL databases were searched for studies reporting the outcome of pregnancies complicated by TTTS stratified according to Quintero stage (IâV). The primary outcome was fetal survival rate according to Quintero stage. Secondary outcomes were gestational age at birth, preterm birth (PTB) before 34, 32 and 28âweeks' gestation and neonatal morbidity. Outcomes are reported according to the different management options (expectant management, laser therapy or amnioreduction) for pregnancies with StageâI TTTS. Only cases treated with laser therapy were considered for those with StagesâIIâIV TTTS and only cases managed expectantly were considered for those with StageâV TTTS. Randomâeffects headâtoâhead metaâanalysis was used to analyze the extracted data.
Results
Twentyâsix studies (2699 twin pregnancies) were included. Overall, 610 (22.6%) pregnancies were diagnosed with Quintero stageâI TTTS, 692 (25.6%) were Stage II, 1146 (42.5%) were Stage III, 247 (9.2%) were Stage IV and four (0.1%) were Stage V. Survival of at least one twin occurred in 86.9% (95%âCI, 84.0â89.7%) (456/552) of pregnancies with StageâI, in 85% (95%âCI, 79.1â90.1%) (514/590) of those with StageâII, in 81.5% (95%âCI, 76.6â86.0%) (875/1040) of those with StageâIII, in 82.8% (95%âCI, 73.6â90.4%) (172/205) of those with StageâIV and in 54.6% (95%âCI, 24.8â82.6%) (5/9) of those with StageâV TTTS. The rate of a pregnancy with no survivor was 11.8% (95%âCI, 8.4â15.8%) (69/564) in those with StageâI, 15.0% (95%âCI, 9.9â20.9%) (76/590) in those with StageâII, 18.6% (95%âCI, 14.2â23.4%) (165/1040) in those with StageâIII, 17.2% (95%âCI, 9.6â26.4%) (33/205) in those with StageâIV and in 45.4% (95%âCI, 17.4â75.2%) (4/9) in those with StageâV TTTS. Gestational age at birth was similar in pregnancies with StagesâIâIII TTTS, and gradually decreased in those with StagesâIV and âV TTTS. Overall, the incidence of PTB and neonatal morbidity increased as the severity of TTTS increased, but data on these two outcomes were limited by the small sample size of the included studies. When stratifying the analysis of pregnancies with StageâI TTTS according to the type of intervention, the rate of fetal survival of at least one twin was 84.9% (95%âCI, 70.4â95.1%) (94/112) in cases managed expectantly, 86.7% (95%âCI, 82.6â90.4%) (249/285) in those undergoing laser therapy and 92.2% (95%âCI, 84.2â97.6%) (56/60) in those after amnioreduction, while the rate of double survival was 67.9% (95%âCI, 57.0â77.9%) (73/108), 69.7% (95%âCI, 61.6â77.1%) (203/285) and 80.8% (95%âCI, 62.0â94.2%) (49/60), respectively.
Conclusions
Overall survival in monochorionic diamniotic pregnancies affected by TTTS is higher for earlier Quintero stages (I and II), but fetal survival rates are moderately high even in those with StageâIII or âIV TTTS when treated with laser therapy. Gestational age at birth was similar in pregnancies with StagesâIâIII TTTS, and gradually decreased in those with StagesâIV and âV TTTS treated with laser and expectant management, respectively. In pregnancies affected by StageâI TTTS, amnioreduction was associated with slightly higher survival compared with laser therapy and expectant management, although these findings may be confirmed only by future headâtoâhead randomized trials
Search for Periodic Gravitational Wave Sources with the EXPLORER detector
We have developed a procedure for the search of signals from periodic sources in the data of gravitational wave detectors. We report here the analysis of one year of data from the resonant detector Explorer, searching for sources located in the Galactic Center (GC). No signals with amplitude greater than h-bar = 2.9Ă10â24, in the range 921.32â921.38 Hz, were observed using data collected over a time period of 95.7 days, for a source located at alpha= 17.70±0.01 h and delta= â29.00±0.05 deg. Our procedure can be extended for any assumed position in the sky and for a more general all-sky search, with the proper frequency correction to account for the spin-down and Doppler effects
Detection of high energy cosmic rays with the resonant gravitational wave detector NAUTILUS and EXPLORER
The cryogenic resonant gravitational wave detectors NAUTILUS and EXPLORER,
made of an aluminum alloy bar, can detect cosmic ray showers. At temperatures
above 1 K, when the material is in the normal conducting state, the measured
signals are in good agreement with the values expected based on the cosmic rays
data and on the thermo-acoustic model. When NAUTILUS was operated at the
temperature of 0.14 K, in superconductive state, large signals produced by
cosmic ray interactions, more energetic than expected, were recorded. The
NAUTILUS data in this case are in agreement with the measurements done by a
dedicated experiment on a particle beam. The biggest recorded event was in
EXPLORER and excited the first longitudinal mode to a vibrational energy of
about 670 K, corresponding to about 360 TeV absorbed in the bar. Cosmic rays
can be an important background in future acoustic detectors of improved
sensitivity. At present, they represent a useful tool to verify the
gravitational wave antenna performance.Comment: submitted to Astroparticle Physic
A Cross-correlation method to search for gravitational wave bursts with AURIGA and Virgo
We present a method to search for transient GWs using a network of detectors
with different spectral and directional sensitivities: the interferometer Virgo
and the bar detector AURIGA. The data analysis method is based on the
measurements of the correlated energy in the network by means of a weighted
cross-correlation. To limit the computational load, this coherent analysis step
is performed around time-frequency coincident triggers selected by an excess
power event trigger generator tuned at low thresholds. The final selection of
GW candidates is performed by a combined cut on the correlated energy and on
the significance as measured by the event trigger generator. The method has
been tested on one day of data of AURIGA and Virgo during September 2005. The
outcomes are compared to the results of a stand-alone time-frequency
coincidence search. We discuss the advantages and the limits of this approach,
in view of a possible future joint search between AURIGA and one
interferometric detector.Comment: 11 pages, 6 figures, submitted to CQG special issue for Amaldi 7
Proceeding
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