550 research outputs found

    On the existence of conformal Killing horizons in LRS spacetimes

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    Let MM be a locally rotationally symmetric spacetime, and ξa\xi^a a conformal Killing vector for the metric on MM, lying in the subspace spanned by the unit timelike direction and the preferred spatial direction, and with non-constant components. Under the assumption that the divergence of ξa\xi^a has no critical point in MM, we obtain the necessary and sufficient condition for ξa\xi^a to generate a conformal Killing horizon. It is shown that ξa\xi^a generates a conformal Killing horizon if and only if either of the components (which coincide on the horizon) is constant along its orbits. That is, a conformal Killing horizon can be realized as the set of critical points of the variation of the component(s) of the conformal Killing vector along its orbits. Using this result, a simple mechanism is provided by which to determine if an arbitrary vector in an expanding LRS spacetime is a conformal Killing vector that generates a conformal Killing horizon. In specializing the case for which ξa\xi^a is a special conformal Killing vector, provided that the gradient of the divergence of ξa\xi^a is non-null, it is shown that LRS spacetimes cannot admit a special conformal Killing vector field, thereby ruling out conformal Killing horizons generated by such vector fields.Comment: 16 pages, no figure, minor typos corrected, accepted for publication in Gen. Relativ. Gravi

    Existence of gradient CKV and gradient conformally stationary LRS spacetimes

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    In this work, we study the existence of gradient CKVs in locally rotationally symmetric spacetimes, those CKVs in the subspace spanned by the tangent to observers' congruence and that of the preferred spatial direction, allowing us to provide a (partial) characterization of gradient conformally static (GCSt) LRS solutions. Irrrotational solutions with non-zero spatial twist admit an irrotational timelike gradient conformal Killing vector field and hence are GCSt. In the case that both the vorticity and twist vanish, we obtain the necessary and sufficient condition for the spacetime to admit a gradient CKV. This is given by a single wave-like PDE, whose solutions are in bijection to the gradient CKVs on the spacetime. We then introduce a characterization of these spacetimes as GCSt using the character of the divergence of the CKV, provided that the metric functions of the spacetimes obey certain inequalities.Comment: 13 pages, no figure, Major modifications: The title has been changed in accordance with the modified content of the paper; Updated presentation of results; Some new results of characterization of gradient conformally stationary LRS spacetimes; all comments/suggestions are welcom

    Horizon area bound and MOTS stability in locally rotationally symmetric solutions

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    In this paper, we study the stability of marginally outer trapped surfaces (MOTS), foliating horizons of the form r=X(τ)r=X(\tau), embedded in locally rotationally symmetric class II perfect fluid spacetimes. An upper bound on the area of stable MOTS is obtained. It is shown that any stable MOTS of the types considered in these spacetimes must be strictly stably outermost, that is, there are no MOTS ``outside" of and homologous to S\mathcal{S}. Aspects of the topology of the MOTS, as well as the case when an extension is made to imperfect fluids, are discussed. Some non-existence results are also obtained. Finally, the ``growth" of certain matter and curvature quantities on certain unstable MOTS are provided under specified conditions.Comment: 21 pages, Submitted to CQG, comments are welcom

    Use of Foley\u27s catheter balloon tamponade to control placental site bleeding resulting from major placenta previa during cesarean section

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    Aim: To evaluate the effect of 2-way Foley\u27s catheter balloon tamponade on controlling immediate postpartum hemorrhage (PPH) in cases of major placenta previa during cesarean section (CS). Methods: We evaluated women with placenta previa from May to November 2015. Women with immediate PPH during CS due to major placenta previa were managed by 2-way Foley\u27s catheter balloon tamponade when medical treatment failed, and before any surgical intervention. Results: Twenty patients, had major placenta previa, were delivered by elective CS and complicated by immediate PPH. Three placenta accreta patients (15%) underwent hysterectomy, 17 (85%) were managed by the 2-way Foley\u27s catheter balloon tamponade. In two patients, Foley\u27s catheter balloon failed to control bleeding and hysterectomy was done immediately. However, Foley\u27s catheter balloon successfully treated the remaining 15 patients. The median bleeding during the operation was 1522.5 (± 619.29) ml. None of them presented complications related to this procedure or required any further invasive surgery. Conclusion: The 2-way Foley\u27s catheter tamponade could be an option to control immediate postpartum hemorrhage resulting from major placenta previa during the cesarean section. This method is simple, cheap, nearly non-invasive and should be considered to reduce the risk of peripartum hysterectomy

    Undiagnosed endometrial abnormalities in women with normal hysterosalpingography scheduled for IVF: prospective evaluation of three-dimensional transvaginal ultrasound versus office hysteroscopy

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    Objectives: To compare the diagnostic accuracy of three-dimensional transvaginal ultrasound (3D-US) to office hysteroscopy (OH) in the screening of uterine cavity with normal hysterosalpingography (HSG) findings for subtle endometrial abnormalities before in vitro-fertilization (IVF). Methods: A prospective cohort cost-modeling study was carried out in a University hospital. We included 120 infertile women with a normal uterine cavity on HSG scheduled for IVF. All cases were evaluated by 3D-US, and the results were compared with OH findings. Results: OH revealed cavitary endometrial lesions (CLs) in thirty-four women (28.3%). Endometrial polyps were the most common detected lesions (16, 47.1%). 3D-US had 88.2% sensitivity, 96.5% specificity, 90.9% positive predictive value, 95.4% negative predictive value, and 94.2% overall accuracy for CLs. The overall agreement between 3D-US and OH was near-perfect (κ=0.86, 95% CI=0.75-0.96). Irregular menstrual bleeds and prior endometrial procedures were significant predictors for CLs (aOR=24.96, 95% CI=2.71–230.04, P=0.005, aOR=9.16, 95% CI=2.13–39.3, P=0.002, respectively). A selective screening strategy discerning OH to women with these predictors and/or women with abnormal 2D-US would have an NPV of 92.8 % with substantial cost benefits. Conclusions: In the pre-IVF work up, 3D-US, a non-invasive imaging modality, seems to be nearly comparable to OH. Office hysteroscopy screening prioritizing women with abnormal 2D-US, irregular menstrual periods and/or prior endometrial traumatization could yield a satisfactory cost-effective approach for identifying endometrial lesions

    NEGATIVE INTERRELATIONSHIP BETWEEN NUMBER OF BERSEEM CUTS AND COTTON YIELD AS A FOLLOWING CROP

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    The present investigation was carried out at the Experimental Farm of the Faculty of Agriculture at Fayoum, Cario University at Dalla, Fayoum Governorate during the two seasons 2000/2001 and 2001/2002. The aim of this investigation was to study the effect of organic manure and number of berseem cuts on cotton yield and its components and fiber traits. The obtained results indicate that only plant height at harvest, number of fruiting branches / plant and the height of the 1st fruiting branch were significantly affected by organic manure (O.M.) application. On the other hand, organic manure did not affect significantly the seed cotton yield, yield components and fiber quality traits. Cotton planting dates affected significantly all studied vegetative growth, seed cotton yield, yield components and fiber quality traits. Early planting date (1st week of March) showed significant superiority over the other two planting dates (1st week of April & May) in number of fruiting branches/ plant, number of days to 1st flower appearance and 1st boll opening, number and weight of open bolls/ plant in the 1st& 2nd pickings, seed cotton yield, lint percentages and studied fiber quality traits. The decreases in the total seed cotton yield attributed to the late planting dates (1st week of April & May) amounted 26.4 and 84.8% and 30.6 and 84.1% of  March planting with the treatments of 10 and 20 m3/ fad organic manure, respectively

    Fahmy's four quadrant sutures: a new technique for control of blood loss during cesarean delivery for placenta previa

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    Background: The objective of this study is to assess the efficacy and safety of Fahmy's four quadrant suture technique (FFQS) in controlling blood loss during cesarean delivery for placenta previa (PP).Methods: The study was carried out in a tertiary University Hospital between January 2017 to December 2017 involved 12 women with heavy bleeding occurred after removal of the placenta from the lower section during cesarean delivery for PP. The FFQS technique consisted of two sutures to ligate the uterine branches on both sides and two sutures on the anterior and posterior wall of the lower uterine segment. Details regarding the management and maternal outcomes were recorded.Results: The mean age of the study participants was 29.58±5.29 years and the mean parity was 2.25±1.14. The mean gestational age at termination of pregnancy was 36.91±1.38 weeks.  The mean duration of the whole surgery was 78.75±43.28 minutes, while the mean duration of FFQS technique was only 10±2.09 minutes. The technique was exclusively effective in 8 out of 12 cases (66.67%) while 2 cases needed bilateral internal iliac artery ligation and 2 cases needed hysterectomy. The mean amount of blood loss in all cases was 2433.33±833.76 ml. the mean amount of transfused packed RBCs was 3.92±1.68 units and fresh frozen plasma (FFP) was 3.42±1.44 units. All cases had uneventful postoperative course and no mortality cases in present series.Conclusions: The new technique; FFQS represents a rapid, effective, and inexpensive opportunity for women with bleeding from the lower segment of uterus due to PP. This simple procedure should be attempted before other complex measures to achieve good hemostasis

    The unexpected presence of a huge cystic hygroma with thanatophoric dysplasia type I: a case report

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    Introduction: The presence of a thin-walled, multicystic structure posterior to the fetal head and neck with an intact vertebral column is known as a cystic hygroma. Thanatophoric dysplasia is the most lethal skeletal dysplasia. Thanatophoric dysplasia (TD) is an autosomal dominant disorder with two phenotypes. TD type I is characterized by a normal shaped skull with bowed femurs and micromelia, while TD type II is characterized by straight femurs with a clover-leaf deformity of the skull and micromelia. We report here a case of thanatophoric dysplasia type I associated with cystic hygroma, this association needs further evaluation. Case history: A 30 year old woman was referred at 26 weeks of gestation because of marked polyhydramnios. Ultrasonographic examination of the fetus revealed a narrow chest, protuberant abdomen, short curved femur, normal shaped skull with accidentally cystic hygroma were present. No other anomalies were detected. We explained to the patient the nature and severity of the anomaly and the patient preferred the termination of pregnancy. Induction of abortion was done successfully. Conclusion: This case report has highlighted the association between cystic hygroma and thanatophoric dysplasia type I. To our knowledge, this is the first report in the literature reporting the association of cystic hygroma and thanatophoric dysplasia type I. We believe that this case is useful for obstetricians and pediatricians. We also highly recommend the genetic evaluation of the fetus and parents

    Synthesis, Characterization, and Biological Activity of N1-Methyl-2-(1H-1,2,3-Benzotriazol-1-y1)-3-Oxobutan- ethioamide Complexes with Some Divalent Metal (II) Ions

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    A new series of Zn2+, Cu2+, Ni2+, and Co2+ complexes of N1-methyl-2-(1H-1,2,3-benzotriazol-1-yl)-3-oxobutanethioamide (MBOBT), HL, has been synthesized and characterized by different spectral and magnetic measurements and elemental analysis. IR spectral data indicates that (MBOBT) exists only in the thione form in the solid state while 13C NMR spectrum indicates its existence in thione and thiole tautomeric forms. The IR spectra of all complexes indicate that (MBOBT) acts as a monobasic bidentate ligand coordinating to the metal(II) ions via the keto-oxygen and thiolato-sulphur atoms. The electronic spectral studies showed that (MBOBT) bonded to all metal ions through sulphur and nitrogen atoms based on the positions and intensity of their charge transfer bands. Furthermore, the spectra reflect four coordinate tetrahedral zinc(II), tetragonally distorted copper(II), square planar nickel(II), and cobalt(II) complexes. Thermal decomposition study of the complexes was monitored by TG and DTG analyses under N2 atmosphere. The decomposition course and steps were analyzed and the activation parameters of the nonisothermal decomposition are determined. The isolated metal chelates have been screened for their antimicrobial activities and the findings have been reported and discussed in relation to their structures
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