Quasi dynamical symmetry in an interacting boson model phase transition

The oft-observed persistence of symmetry properties in the face of strong symmetry-breaking interactions is examined in the SO(5)-invariant interacting boson model. This model exhibits a transition between two phases associated with U(5) and O(6) symmetries, respectively, as the value of a control parameter progresses from 0 to 1. The remarkable fact is that, for intermediate values of the control parameter, the model states exhibit the characteristics of its closest symmetry limit for all but a relatively narrow transition region that becomes progressively narrower as the particle number of the model increases. This phenomenon is explained in terms of quasi-dynamical symmetry.Comment: 4 figure

Measurement of the local Jahn-Teller distortion in LaMnO_3.006

The atomic pair distribution function (PDF) of stoichiometric LaMnO_3 has been measured. This has been fit with a structural model to extract the local Jahn-Teller distortion for an ideal Mn(3+)O_6 octahedron. These results are compared to Rietveld refinements of the same data which give the average structure. Since the local structure is being measured in the PDF there is no assumption of long-range orbital order and the real, local, Jahn-Teller distortion is measured directly. We find good agreement both with published crystallographic results and our own Rietveld refinements suggesting that in an accurately stoichiometric material there is long range orbital order as expected. The local Jahn-Teller distortion has 2 short, 2 medium and 2 long bonds.Comment: 5 pages, 3 postscript figures, minor change

Design of a freeform two-reflector system to collimate and shape a point source distribution

In this paper we propose a method to compute a freeform reflector system for collimating and shaping a beam from a point source. We construct these reflectors such that the radiant intensity of the source is converted into a desired target. An important generalization in our approach compared to previous research is that the output beam can be in an arbitrary direction. The design problem is approached by using a generalized Monge-Amp\`ere equation. This equation is solved using a least-squares algorithm for non-quadratic cost functions. This algorithm calculates the optical map, from which we can then compute the surfaces. We test our algorithm on two cases. First we consider a uniform source and target distribution. Next, we use the model of a laser diode light source and a ring-shaped target distribution

Obstetric intensive care unit admission: a 2-year nationwide population-based cohort study

As part of a larger nationwide enquiry into severe maternal morbidity, our aim was to assess the incidence and possible risk factors of obstetric intensive care unit (ICU) admission in the Netherlands. In a 2-year nationwide prospective population-based cohort study, all ICU admissions during pregnancy, delivery and puerperium (up to 42 days postpartum) were prospectively collected. Incidence, case fatality rate and possible risk factors were assessed, with special attention to the ethnic background of women. All 98 Dutch maternity units participated in the study. There were 847 obstetric ICU admissions in 358,874 deliveries, the incidence being 2.4 per 1,000 deliveries. Twenty-nine maternal deaths occurred, resulting in a case fatality rate of 1 in 29 (3.5%). Incidence of ICU admission varied largely across the country. Thirty-three percent of all cases of severe maternal morbidity were admitted to an ICU. Most frequent reasons for ICU admission were major obstetric haemorrhage (48.6%), hypertensive disorders of pregnancy (29.3%) and sepsis (8.1%). Assisted ventilation was needed in 34.8%, inotropic support in 8.8%. In univariable analysis, non-Western immigrant women had a 1.4-fold (95% CI 1.2-1.7) increased risk of ICU admission as compared to Western women. Initial antenatal care by an obstetrician was associated with a higher risk and home delivery with a lower risk of ICU admission. Population-based incidence of obstetric ICU admission in the Netherlands was 2.4 per 1,000 deliveries. Obstetric ICU admission accounts for only one-third of all cases of severe maternal morbidity in the Netherlands.Public Health and primary carePrevention, Population and Disease management (PrePoD

Management of prolonged first stage of labour in a low-resource setting: lessons learnt from rural Malawi

Background Caesarean sections without medical indication cause substantial maternal and perinatal ill-health, particularly in low-income countries where surgery is often less safe. In presence of adequate labour monitoring and by appropriate use of evidence-based interventions for prolonged first stage of labour, unnecessary caesarean sections can be avoided. We aim to describe the incidence of prolonged first stage of labour and the use of amniotomy and augmentation with oxytocin in a low-resource setting in Malawi. Methods Retrospective analysis of medical records and partographs of all women who gave birth in 2015 and 2016 in a rural mission hospital in Malawi. Primary outcomes were incidence of prolonged first stage of labour based on partograph tracings, caesarean section indications and utilization of amniotomy and oxytocin augmentation. Results Out of 3246 women who gave birth in the study period, 178 (5.2%) crossed the action line in the first stage of labour, of whom 21 (11.8%) received oxytocin to augment labour. In total, 645 women gave birth by caesarean section, of whom 241 (37.4%) with an indication 'prolonged first stage of labour'. Only 113 (46.9%) of them crossed the action line and in 71/241 (29.5%) membranes were still intact at the start of caesarean section. Excluding the 60 women with prior caesarean sections, 14/181 (7.7%) received oxytocin prior to caesarean section for augmentation of labour. Conclusion The diagnosis prolonged first stage of labour was often made without being evident from labour tracings and two basic obstetric interventions to prevent caesarean section, amniotomy and labour augmentation with oxytocin, were underused.Perioperative Medicine: Efficacy, Safety and Outcome (Anesthesiology/Intensive Care

Maternal mortality: near-miss events in middle-income countries, a systematic review

Objective To describe the incidence and main causes of maternal near-miss events in middle-income countries using the World Health Organization's (WHO) maternal near-miss tool and to evaluate its applicability in these settings. Methods We did a systematic review of studies on maternal near misses in middle-income countries published over 2009-2020. We extracted data on number of live births, number of maternal near misses, major causes of maternal near miss and most frequent organ dysfunction. We extracted, or calculated, the maternal near-miss ratio, maternal mortality ratio and mortality index. We also noted descriptions of researchers'experiences and modifications of the WHO tool for local use. Findings We included 69 studies from 26 countries (12 lower-middle- and 14 upper-middle-income countries). Studies reported a total of 50 552 maternal near misses out of 10 450 482 live births. Median number of cases of maternal near miss per 1000 live births was 15.9 (interquartile range, IQR: 8.9-34.7) in lower-middle- and 7.8 (IQR: 5.0-9.6) in upper-middle-income countries, with considerable variation between and within countries. The most frequent causes of near miss were obstetric haemorrhage in 19/40 studies in lower-middleincome countries and hypertensive disorders in 15/29 studies in upper-middle-income countries. Around half the studies recommended adaptations to the laboratory and management criteria to avoid underestimation of cases of near miss, as well as clearer guidance to avoid different interpretations of the tool. Conclusion In several countries, adaptations of the WHO near-miss tool to the local context were suggested, possibly hampering international comparisons, but facilitating locally relevant audits to learn lessons.Research into fetal development and medicin

Death receptor 5 is activated by fucosylation in colon cancer cells

The remarkable pro-apoptotic properties of tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) have led to considerable interest in this protein as a potential anticancer therapeutic. However, TRAIL is largely ineffective in inducing apoptosis in certain cancer cells, and the mechanisms underlying this selectivity are unknown. In colon adenocarcinomas, posttranslational modifications including O- and N- glycosylation of death receptors were found to correlate with TRAIL-induced apoptosis. Additionally, mRNA levels of fucosyltransferase 3 (FUT3) and 6 (FUT6) were found to be high in the TRAIL-sensitive colon adenocarcinoma cell line COLO 205. In this study, we use agonistic receptor-specific TRAIL variants to dissect the contribution of FUT3 and FUT6-mediated fucosylation to TRAIL-induced apoptosis via its two death receptors, DR4 and DR5. Triggering of apoptosis by TRAIL revealed that the low FUT3/6-expressing cells DLD-1 and HCT 116 are insensitive to DR5 but not to DR4-mediated apoptosis. By contrast, efficient apoptosis is mediated via both receptors in high FUT3/6-expressing COLO 205 cells. The reconstitution of FUT3/6 expression in DR5-resistant cells completely restored TRAIL sensitivity via this receptor, while only marginally enhancing apoptosis via DR4 at lower TRAIL concentrations. Interestingly, we observed that induction of the salvage pathway by external administration of l-fucose restores DR5-mediated apoptosis in both DLD-1 and HCT 116 cells. Finally, we show that fucosylation influences the ligand-independent receptor association that leads to increased death inducing signalling complex (DISC) formation and caspase-8 activation. Taken together, these results provide evidence for the differential impact of fucosylation on signalling via DR4 or DR5. These findings provide novel opportunities to enhance TRAIL sensitivity in colon adenocarcinoma cells that are highly resistant to DR5-mediated apoptosis

Nanosized Sodium-Doped Lanthanum Manganites: Role of the Synthetic Route on their Physical Properties

In this paper we present the results of the synthesis and characterisation of nanocrystalline La1-xNaxMnO3+delta samples. Two synthetic routes were employed: polyacrylamide-based sol-gel and propellant synthesis. Pure, single phase materials were obtained with grain size around 35 nm for the sol-gel samples and around 55 nm for the propellant ones, which moreover present a more broaden grain size distribution. For both series a superparamagnetic behaviour was evidenced by means of magnetisation and EPR measurements with peculiar features ascribable to the different grain sizes and morphology. Preliminary magnetoresistivity measurements show enhanced low-field (< 1 T) magnetoresistance values which suggest an interesting applicative use of these manganites.Comment: 31 Pages 10 Figures to appear in Chem. Mate

Mean-field analysis of interacting boson models with random interactions

We investigate the origin of the regular features observed in numerical studies of the interacting boson model with random interactions, in particular the dominance of L=0 ground states and the occurrence of vibrational and rotational band structures. It is shown that all of these properties can be interpreted and explained in terms of a Hartree-Bose mean-field analysis, in which different regions of the parameter space are associated with geometric shapes. The same conclusions hold for the vibron model.Comment: 8 pages, 4 figures, 2 tables. Physical Review C, in pres

Predictors of HIV Among 1 Million Clients in High-Risk Male Populations in Tanzania

The World Health Organization identified men as an essential group to target with HIV testing and treatment strategies;: men who have sex with men (MSM) and male clients of female sex workers (CFSW) account for 35% of new HIV infections globally. Using a cross-sectional design from a community-based HIV prevention project in Tanzania (October 2015-September 2018) and multivariable logistic regression, we identified predictors of HIV seropositivity among men. Of 1,041,343 men on their initial visit to the project, 36,905 (3.5%) were MSM; 567,005 (54.5%) were CFSW; and 437,343 (42.0%) were other men living near hotspots (OMHA). Three predictors of HIV seropositivity emerged across all three groups: being uncircumcised, having sexually transmitted infection symptoms, and harmful drinking of alcohol before sex. Any reported form of gender-based violence among MSM and OMHA and inconsistent condom use among CFSW were associated with HIV seropositivity. These findings may inform community HIV strategies like self-testing, delivery of pre-exposure prophylaxis and antiretroviral therapy, and behavioral change communication targeting men at higher risk of infection