University of Liverpool

About: University of Liverpool is a education organization based out in Liverpool, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 40406 authors who have published 94388 publications receiving 3188970 citations. The organization is also known as: Liverpool University & The University of Liverpool.

Trigeminal neuralgia—pathophysiology, diagnosis and current treatment

Abstract: The ®rst known description of trigeminal neuralgia (TGN), or a similar condition, was written in the second century AD by Aretaeus of Cappadocia, a contemporary of Galen. Also known for his descriptions of migraine, he makes reference to a pain in which `spasm and distortion of the countenance take place'. Jujani, an 11th century Arab physician, mentions unilateral facial pain causing spasms and anxiety in his writings. Interestingly, he suggests that the cause of the pain is `the proximity of the artery to the nerve'. The ®rst full account of TGN was published in 1773 when John Fothergill presented a paper to the Medical Society of London. He described the typical features of the condition in detail, including paroxysms of unilateral facial pain, evoked by eating or speaking or touch, starting and ending abruptly, and associated with anxiety. Some time earlier, Nicolaus Andre had used the term `tic douloureux' to describe what he thought was a new clinical entity. However, it has been suggested, that no more than two of the patients he described in fact had TGN. Sporadic observations later in the 18th and 19th century by Pujol, Chapman and Tiffany helped to complete the clinical picture and differentiate TGN from common facial pain conditions such as toothache. In the early 20th century, Oppenheim alluded to an association between multiple sclerosis (MS) and TGN and Patrick commented on its familial incidence. A wide range of treatments was in use by the beginning of the last century. Modern neurosurgical treatment can be traced back to 1925 when the concept of vascular compression was introduced. However, it took over half a century before microvascular decompression (MVD) gained wide-spread acceptance as a treatment method. Gardner and Miklos promoted the theory and modi®ed the technique further in the 1950s and 1960s. It was not until the large case series published in 1970s by Jannetta that a major shift in neurosurgical practice began to appear. Neuroablative procedures kept evolving throughout the century, with attempts to balance the adverse effects of neural injury with suf®cient pain control. Radiosurgery is the latest innovation in this process. Pharmacotherapy had little success in this condition until Bergouignan's discovery in 1942 that phenytoin was effective in preventing pain paroxysms. Soon, following the introduction of carbamazepine for treatment of epilepsy, controlled trials were published showing its superiority over placebo in TGN. Since then, anticonvulsants have remained the mainstay of pharmacological treatment, though controlled trials have been surprisingly rare.

Fault overlap zones within developing normal fault systems

Abstract: Overlap zones between normal faults have been studied using a variety of 2D and 3D seismic reflection datasets. The overlaps are of two types, (i) relay zones in which displacement is transferred between the overlapping faults and (ii) non-relay overlaps in which displacement is not transferred. Overlap zones are continually formed and destroyed during the growth of a fault system. Overlap zones are formed either by interference between initially isolated faults or as a result of bifurcation of a single fault. The mode of overlap formation is reflected in the 3D geometry of the overlapping faults which may be either unconnected or linked at a branch-line or branch-point. Seismic reflection data from regions of growth faulting, and also sandbox analogue data, allow analysis of fault development through time. Reconstructions of the displacement distribution on some faults with sharp bends and associated hanging-wall splays, show that the bends originated as overlap zones which were later breached to form through-going faults. Depending on the displacements of relay-bounding faults, the effect of relay zones on hydrocarbon reservoirs may be to (a) provide structural closure, (b) form gaps in otherwise sealing faults or (c) increase reservoir connectivity.

Performance of $b$-Jet Identification in the ATLAS Experiment

Abstract: The identification of jets containing b hadrons is important for the physics programme of the ATLAS experiment at the Large Hadron Collider. Several algorithms to identify jets containing b hadrons are described, ranging from those based on the reconstruction of an inclusive secondary vertex or the presence of tracks with large impact parameters to combined tagging algorithms making use of multi-variate discriminants. An independent b-tagging algorithm based on the reconstruction of muons inside jets as well as the b-tagging algorithm used in the online trigger are also presented. The b-jet tagging efficiency, the c-jet tagging efficiency and the mistag rate for light flavour jets in data have been measured with a number of complementary methods. The calibration results are presented as scale factors defined as the ratio of the efficiency (or mistag rate) in data to that in simulation. In the case of b jets, where more than one calibration method exists, the results from the various analyses have been combined taking into account the statistical correlation as well as the correlation of the sources of systematic uncertainty.

Amniocentesis and chorionic villus sampling for prenatal diagnosis

Abstract: Background During pregnancy, fetal cells suitable for genetic testing can be obtained from amniotic fluid by amniocentesis (AC), placental tissue by chorionic villus sampling (CVS), or fetal blood. A major disadvantage of second trimester amniocentesis is that the results are available relatively late in pregnancy (after 16 weeks' gestation). Earlier alternatives are chorionic villus sampling (CVS) and early amniocentesis, which can be performed in the first trimester of pregnancy. Objectives The objective of this review was to compare the safety and accuracy of all types of AC (i.e. early and late) and CVS (e.g. transabdominal, transcervical) for prenatal diagnosis. Search methods We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (3 March 2017), ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP; 3 March 2017), and reference lists of retrieved studies. Selection criteria All randomised trials comparing AC and CVS by either transabdominal or transcervical route. Data collection and analysis Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. The quality of the evidence was assessed using the GRADE approach. Main results We included a total of 16 randomised studies, with a total of 33,555 women, 14 of which were deemed to be at low risk of bias. The number of women included in the trials ranged from 223 to 4606. Studies were categorized into six comparisons: 1. second trimester AC versus control; 2. early versus second trimester AC; 3. CVS versus second trimester AC; 4. CVS methods; 5. Early AC versus CVS; and 6. AC with or without ultrasound. One study compared second trimester AC with no AC (control) in a low risk population (women = 4606). Background pregnancy loss was around 2%. Second trimester AC compared to no testing increased total pregnancy loss by another 1%. The confidence intervals (CI) around this excess risk were relatively large (3.2% versus 2.3 %, average risk ratio (RR) 1.41, 95% CI 0.99 to 2.00; moderate-quality evidence). In the same study, spontaneous miscarriages were also higher (2.1% versus 1.3%; average RR 1.60, 95% CI 1.02 to 2.52; high-quality evidence). The number of congenital anomalies was similar in both groups (2.0% versus 2.2%, average RR 0.93, 95% CI 0.62 to 1.39; moderate-quality evidence). One study (women = 4334) found that early amniocentesis was not a safe early alternative compared to second trimester amniocentesis because of increased total pregnancy losses (7.6% versus 5.9%; average RR 1.29, 95% CI 1.03 to 1.61; high-quality evidence), spontaneous miscarriages (3.6% versus 2.5%, average RR 1.41, 95% CI 1.00 to 1.98; moderate-quality evidence), and a higher incidence of congential anomalies, including talipes (4.7% versus 2.7%; average RR 1.73, 95% CI 1.26 to 2.38; high-quality evidence). When pregnancy loss after CVS was compared with second trimester AC, there was a clinically significant heterogeneity in the size and direction of the effect depending on the technique used (transabdominal or transcervical), therefore, the results were not pooled. Only one study compared transabdominal CVS with second trimester AC (women = 2234). They found no clear difference between the two procedures in the total pregnancy loss (6.3% versus 7%; average RR 0.90, 95% CI 0.66 to 1.23, low-quality evidence), spontaneous miscarriages (3.0% versus 3.9%; average RR 0.77, 95% CI 0.49 to 1.21; low-quality evidence), and perinatal deaths (0.7% versus 0.6%; average RR 1.18, 95% CI 0.40 to 3.51; low-quality evidence). Transcervical CVS may carry a higher risk of pregnancy loss (14.5% versus 11.5%; average RR 1.40, 95% CI 1.09 to 1.81), but the results were quite heterogeneous. Five studies compared transabdominal and transcervical CVS (women = 7978). There were no clear differences between the two methods in pregnancy losses (average RR 1.16, 95% CI 0.81 to 1.65; very low-quality evidence), spontaneous miscarriages (average RR 1.68, 95% CI 0.79 to 3.58; very low-quality evidence), or anomalies (average RR 0.68, 95% CI 0.41 to 1.12; low-quality evidence). We downgraded the quality of the evidence to low due to heterogeneity between studies. Transcervical CVS may be more technically demanding than transabdominal CVS, with more failures to obtain sample (2.0% versus 1.1%; average RR 1.79, 95% CI 1.13 to 2.82, moderate-quality evidence). Overall, we found low-quality evidence for outcomes when early amniocentesis was compared to transabdominal CVS. Spontaneous miscarriage was the only outcome supported by moderate-quality evidence, resulting in more miscarriages after early AC compared with transabdominal CVS (2.3% versus 1.3%; average RR 1.73, 95% CI 1.15 to 2.60). There were no clear differences in pregnancy losses (average RR 1.15, 95% CI 0.86 to 1.54; low-quality evidence), or anomalies (average RR 1.14, 95% CI 0.57 to 2.30; very low-quality evidence). We found one study that examined AC with or without ultrasound, which evaluated a type of ultrasound-assisted procedure that is now considered obsolete. Authors' conclusions Second trimester amniocentesis increased the risk of pregnancy loss, but it was not possible to quantify this increase precisely from only one study, carried out more than 30 years ago. Early amniocentesis was not as safe as second trimester amniocentesis, illustrated by increased pregnancy loss and congenital anomalies (talipes). Transcervical chorionic villus sampling compared with second trimester amniocentesis may be associated with a higher risk of pregnancy loss, but results were quite heterogeneous. Diagnostic accuracy of different methods could not be assessed adequately because of incomplete karyotype data in most studies.