688 research outputs found

    Signatures of a staggered-flux phase in the t-J model with two holes on a 32-site lattice

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    We study the relevance of the staggered-flux phase in the t-J model using a system with two holes on a 32-site lattice with periodic boundary conditions. We find a staggered-flux pattern in the current-current correlation in the lowest energy d-wave state where there is mutual attraction between the holes. This staggered correlation decays faster with distance when the hole binding becomes stronger. This is in complete agreement with a recent study by Ivanov, Lee and Wen (Phys. Rev. Lett. 84, 3958, (2000)) based on the SU(2) theory, and strongly suggests that the staggered-flux phase is a key ingredient in the t-J model. We further show that this staggered-flux pattern does not exist in a state where the holes repel each other. Correlations of the chirality operator S_1.(S_2xS_3) show that the staggered pattern of the chirality is closely tied to the holes.Comment: To appear in Phys. Rev. B (Rapid Communications

    Reducing childbirth-related intrusive memories and PTSD symptoms via a single-session behavioural intervention including a visuospatial task: A proof-of-principle study.

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    Intrusive memories (IMs) of traumatic events are a key symptom of posttraumatic stress disorder (PTSD), and contribute to its maintenance. This translational proof-of-principle study tested whether a single-session behavioural intervention reduced the number of childbirth-related IMs (CB-IMs) and childbirth-related PTSD (CB-PTSD) symptoms, in women traumatised by childbirth. The intervention was assumed to disrupt trauma memory reconsolidation. In this pre-post study, 18 participants, whose traumatic childbirth had occurred between seven months and 6.9 years before, received an intervention combining childbirth-related reminder cues (including the return to maternity unit) with a visuospatial task. They recorded their daily CB-IMs in the two weeks pre-intervention (diary 1), the two weeks post-intervention (diary 2; primary outcome), and in week 5 and 6 post-intervention (diary 3). CB-PTSD symptom severity was assessed five days pre-intervention and one month post-intervention. Compared to diary 1, 15/18 participants had ≥ 50% fewer CB-IMs in diary 2. The median (IQR) reduction of the number of CB-IMs was 81.89% (39.58%) in diary 2, and persisted in diary 3 (n = 17). At one month post-intervention, CB-PTSD symptom severity was reduced by ≥ 50% in 10/18 participants. Of the 8 participants with a CB-PTSD diagnosis pre-intervention, none met diagnostic criteria post-intervention. The intervention was rated as highly acceptable. The design limits the causal interpretation of observed improvements. This is the first time such a single-session behavioural intervention was tested for old and real-life single-event trauma. The promising results justify a randomized controlled trial, and may be a first step toward an innovative CB-PTSD treatment

    Cu KK-edge Resonant Inelastic X-Ray Scattering in Edge-Sharing Cuprates

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    We present calculations for resonant inelastic x-ray scattering (RIXS) in edge-shared copper oxide systems, such as CuGeO3_{3} and Li2_{2}CuO2_{2}, appropriate for hard x-ray scattering where the photoexcited electron lies above oxygen 2p and copper 3d orbital energies. We perform exact diagonalizations of the multi-band Hubbard and determine the energies, orbital character and resonance profiles of excitations which can be probed via RIXS. We find excellent agreement with recent results on Li2_{2}CuO2_{2} and CuGeO3_{3} in the 2-7 eV photon energy loss range.Comment: Updated with new data, expanded 9 pages, 9 figure

    Cluster Property and Robustness of Ground States of Interacting Many Bosons

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    We study spatial correlation functions of local operators of interacting many bosons confined in a box of a large, but volume V, for various `ground states' whose energy densities are almost degenerate. The ground states include the coherent state of interacting bosons (CSIB), the number state of interacting bosons (NSIB), and the number-phase squeezed state of interacting bosons, which interpolates between the CSIB and NSIB. It was shown previously that only the CSIB is robust (i.e., does not decohere for a macroscopically long time) against the leakage of bosons into an environment. We show that for the CSIB the spatial correlation of any local operators A(r) and B(r') (which are localized around r and r', respectively) vanishes as |r - r' | \sim V^{1/3} \to \infty, i.e., the CSIB has the `cluster property.' In contrast, the other ground states do not possess the cluster property. Therefore, we have successfully shown that the robust state has the cluster property. This ensures the consistency of the field theory of bosons with macroscopic theories.Comment: We have replaced the manuscript in order to update the reference list and to fix typos. (5 pages, no figures) In the final manuscript, a few sentences have added for more detailed explanation. Journal PDF at http://jpsj.jps.or.jp/journal/JPSJ-71-1.htm

    Informing about childbirth without increasing anxiety: a qualitative study of first-time pregnant women and partners' perceptions and needs.

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    Complications requiring medical interventions during childbirth are far from rare, even after uncomplicated pregnancies. It is often a challenge for maternity healthcare professionals to know how to prepare future parents for these eventualities without causing unnecessary anxiety. Studies on traumatic birth experiences have shown that feelings of loss of control, insufficient information, and lack of participation in medical decisions during childbirth are factors of difficult experiences. However, little is known about the information and communication needs of expectant parents about childbirth during the prenatal period. To gain a deeper understanding of the information and communication needs of first-time pregnant women and partners, we explored their perceptions and expectations for their upcoming childbirth, and the actions they initiated to prepare for it. Semi-structured interviews were conducted individually with first-time pregnant women and partners of pregnant women aged 18 years or older, with an uncomplicated pregnancy. Thematic analysis was used to identify themes and sub-themes. Twenty expectant parents (15 pregnant women and five partners of pregnant women) were interviewed. Six themes were identified: Childbirth event; Childbirth experience; Childbirth environment; Organisation of care; Participation in decision making; Roles within the couple and transition to parenthood. This study contributes to a better understanding of the information needs of future parents expecting their first child. Results highlighted that the notion of "childbirth risks" went beyond the prospect of complications during birth, but also encompassed concerns related to a feeling of loss of control over the event. Expectant parents showed an ambivalent attitude towards consulting risk information, believing it important to prepare for the unpredictability of childbirth, while avoiding information they considered too worrying. They expressed a desire to receive concrete, practical information, and needed to familiarise themselves in advance with the birth environment. Establishing a respectful relationship with the healthcare teams was also considered important. The findings suggest that information on childbirth should not be limited to the transmission of knowledge, but should primarily be based on the establishment of a relationship of trust with healthcare professionals, taking into account each person's individual values and expectations

    The pregnancy experiences and antenatal care services of Chinese migrants in Switzerland: a qualitative study.

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    Differences in reproductive health outcomes according to the mothers' origins have been reported in Switzerland, for example, women from European countries and non-European countries. The Swiss Federal Office of Public Health has therefore called for specific Swiss-wide studies on migrant populations. This study explores the pregnancy and antenatal care experiences of Chinese migrants in Switzerland, intending to clarify their maternity care needs. In-depth interviews of 14 Chinese mothers and 13 family members were conducted in Chinese or English and audio recorded. All audio-recordings were transcribed verbatim. All Chinese transcripts were translated into English. Thematic analysis was performed with the assistance of the qualitative data analysis software, MAXQDA Analytics Pro 2020. Five themes were extracted from the transcripts: (1) Motivations and concerns about having children, (2) The merits of the Swiss maternity care system, (3) The inconveniences and barriers of accessing Swiss maternity care services, (4) Strategies to deal with the inconveniences of the Swiss maternity care system, and (5) The need for culturally sensitive care. The results of our study provide new knowledge and understanding of pregnancy experiences and antenatal care services of Chinese mothers and their families in Switzerland. Their unique positive experiences included: family planning, the continuity of maternity services, humane care with the privacy respected, personalized sensitive care needs, preferences for female obstetricians and obstetricians of Asian origin. Several barriers were highlighted, such as information seeking difficulties, communication difficulties, and a rigid appointment system. Reducing barriers enabling access to maternity care services within the Swiss healthcare system is necessary to provide equal quality maternity care for individuals, irrespective of their origins

    Gynecological, reproductive and sexual outcomes after uterine artery embolization for post-partum haemorrage.

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    In this case control study, long-term gynecological, reproductive and sexual outcomes after uterine artery embolization (UAE) for postpartum hemorrhage (PPH) were evaluated. The study was performed in a single referral hospital for PPH in Lausanne from 2003 to 2013. Each woman whose delivery was complicated by PPH and treated by UAE was included, and compared to a control group of women whose delivery was uncomplicated. Cases were matched by maternal age, parity, ethnicity, year and mode of delivery, birth weight and gestational age in a 1-3 ratio. A total of 77 patients treated by UAE for PPH were identified in our obstetrical database. Among them, 63 were included and compared to 189 matched patients (no PPH). The mean interval time between UAE and this study was 8.1 years. Time to menstrual cycle recovery after delivery (3.9 vs 5.6 months, p = 0.66), spotting (7.9% vs 7.2%, p = 0.49), dysmenorrhea (25.4% vs 22.2%, p = 0.60) and amenorrhea (14.3% vs 12.2%, p = 0.66) were similar between the two groups. There was no difference in the FSFI score between the groups (23.2 ± 0.6 vs 23.8 ± 0.4; p = 0.41). However, the interval time to subsequent pregnancy was longer for patients after UAE than the control group (35 vs 18 months, p = 0.002). In case of pregnancy desire, the success rate was lower after UAE compared to controls (55% vs 93.5%, p < 0.001). The rate of PPH was higher in those with previous PPH (6.6% vs 36.4%, p = 0.010). Patients treated by UAE for PPH did not report higher rates of gynecological symptoms or sexual dysfunction compared to patients with uneventful deliveries. The inter-pregnancy interval was increased and the success rate was reduced. In subsequent pregnancies, a higher rate of PPH was observed in those that underwent UAE

    Paternal and maternal long-term psychological outcomes after uterine artery embolization for severe post-partum hemorrhage.

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    This study intend to compare the long-term psychological impact (depression, post-traumatic stress disorder) on both partners between patients that underwent uterine artery embolization (UAE) for post-partum hemorrhage (PPH) and uneventful deliveries. Women who experienced severe PPH treated by UAE in our institution between 2003 and 2013 were identified in our obstetrical database. These cases were matched to controls with uneventful deliveries. Matching criteria were maternal age, parity, ethnicity, year of delivery, birthweight, gestational age and mode of delivery. Patients and their partners completed validated questionnaires measuring post-traumatic stress (TSQ), as well as depression symptoms (MINI). A total of 63 cases of PPH and 189 matched controls (1:3) participated in a study exploring gynecological and obstetrical outcomes. With a mean of 8 years post-index delivery, patients after PPH showed increased risk of depression (p = 0.015) and post-traumatic stress disorder (22.2% versus 4.8%, p < 0.005) compared to controls. PPH remains strongly associated with post-traumatic stress disorder, even after adjustment for depression (adjusted odds ratio 5.1; 95% confidence intervals 1.5-17.5). Similarly, partners of patients with PPH showed a propensity to depression (p = 0.029) and post-traumatic stress disorder (11.5% versus 1.5%, p = 0.019). In conclusion, both women and their partners are at increased risk of long-term psychological adverse outcomes after PPH. Couples may benefit from psychological support
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