1,765 research outputs found

    High order magnon bound states in the quasi-one-dimensional antiferromagnet α\alpha-NaMnO2_2

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    Here we report on the formation of two and three magnon bound states in the quasi-one-dimensional antiferromagnet α\alpha-NaMnO2_2, where the single-ion, uniaxial anisotropy inherent to the Mn3+^{3+} ions in this material provides a binding mechanism capable of stabilizing higher order magnon bound states. While such states have long remained elusive in studies of antiferromagnetic chains, neutron scattering data presented here demonstrate that higher order n>2n>2 composite magnons exist, and, specifically, that a weak three-magnon bound state is detected below the antiferromagnetic ordering transition of NaMnO2_2. We corroborate our findings with exact numerical simulations of a one-dimensional Heisenberg chain with easy-axis anisotropy using matrix-product state techniques, finding a good quantitative agreement with the experiment. These results establish α\alpha-NaMnO2_2 as a unique platform for exploring the dynamics of composite magnon states inherent to a classical antiferromagnetic spin chain with Ising-like single ion anisotropy.Comment: 5 pages, 4 figure

    Development of a fixative protocol using formaldehyde and gluteraldehyde for preservation of microbial art on agar plates.

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    Agar art bridges the gap between science and art, using microbes instead of paint. Afterwards, the art can change in response to microbial fluctuation, meaning preservation of the original art is essential. Here, formaldehyde and glutaraldehyde were investigated as preservatives, involving techniques used in healthcare settings to preserve samples. Formaldehyde was tested at 1.0%, 2.0% and 3.7%, w/v, whereas glutaraldehyde was tested at 1% and 2.5%, w/v. Both compounds and respective concentrations were tested for different time periods. Escherichia coli, Serratia marcescens, Staphlococcus aureus and Micrococcus luteus were used as bacteria for "drawing" the works of art. The effectiveness of fixation was determined using integrated densities and visual assessment. Initially, both compounds showed potential promise, albeit with a loss of bacteria. Ser. marcescens was prone to colour changes and glutaraldehyde caused discolouration of agar and bacteria. These could be caused by a pH decrease in the agar, due to residual free aldehyde groups. Reduction of this was tested using 300 mM sodium metabisulfite to neutralize excess aldehydes. This initially led to reduced bacterial loss and avoided colour changes, however measurements 24 h post-fixation showed colour loss to some bacterial clusters. This study found that, depending on the species, use of at least 2% formaldehyde for a short fixation period (typically 1 min) was the most promising approach for the preservation of art. Given the success of this with different bacteria, it would make a good starting combination for anyone trying to fix agar art; depending on the bacterial species used, methodology refinement may be needed for optimisation. This study shows successful fixation and preservation of different bacterial species on agar for the first time. The impact of this is to preserve agar art while making it safe and non-infective to those in contact with the microbial art

    Complications of Subcutaneous Contraception: A Review.

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    Over 62 million women in the United States are of childbearing age and 60% of them use contraception. Subcutaneous contraceptives include implantable contraceptives and subcutaneous injections. Implantable contraception involves subdermal time-release of synthetic progestin, which allows for several years of continuous, highly effective contraception. Its main effects are inhibition of ovulation and thickening of the cervical mucus. Many complications have been associated with subcutaneous contraception, including menstrual disturbances, headache, weight gain, acne, dizziness, mood disturbances, nausea, lower abdominal pain, hair loss, loss of libido, pain at the implant site, neuropathy, and follicular cysts. Using standard search engines, the complications of subcutaneous contraception are reviewed. Patients should be adequately counseled on the possible complications and side effects of subcutaneous contraception to help them make an informed decision when choosing the right contraceptive to meet their needs

    Applying the Information-Motivation-Behavioral Skills Model of HIV- Risk to Youth in Psychiatric Care

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    This study examined the utility of cognitive and behavioral constructs (AIDS in-formation, motivation, and behavioral skills) in explaining sexual risk taking among 172 12–20–year-old ethnically diverse urban youths in outpatient psy-chiatric care. Structural equation modeling revealed only moderate support for the model, explaining low to moderate levels of variance in global sexual risk taking. The amount of explained variance improved when age was included as a predictor in the model. Findings shed light on the contribution of AIDS informa-tion, motivation, and behavioral skills to risky sexual behavior among teens re-ceiving outpatient psychiatric care. Results suggest that cognitive and behavioral factors alone may not explain sexual risk taking among teens whose cognitive and emotional deficits (e.g., impaired judgment, poor reality testing, affect dysregulation) interfere with HIV preventive behavior. The most powerful ex-planatory model will likely include a combination of cognitive, behavioral, developmental, social (e.g., family), and personal (e.g., psychopathology) risk mechanisms

    Infarct size and left ventricular remodelling after preventive percutaneous coronary intervention

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    Objective: We hypothesised that, compared with culprit-only primary percutaneous coronary intervention (PCI), additional preventive PCI in selected patients with ST-elevation myocardial infarction with multivessel disease would not be associated with iatrogenic myocardial infarction, and would be associated with reductions in left ventricular (LV) volumes in the longer term. Methods: In the preventive angioplasty in myocardial infarction trial (PRAMI; ISRCTN73028481), cardiac magnetic resonance (CMR) was prespecified in two centres and performed (median, IQR) 3 (1, 5) and 209 (189, 957) days after primary PCI. Results: From 219 enrolled patients in two sites, 84% underwent CMR. 42 (50%) were randomised to culprit-artery-only PCI and 42 (50%) were randomised to preventive PCI. Follow-up CMR scans were available in 72 (86%) patients. There were two (4.8%) cases of procedure-related myocardial infarction in the preventive PCI group. The culprit-artery-only group had a higher proportion of anterior myocardial infarctions (MIs) (55% vs 24%). Infarct sizes (% LV mass) at baseline and follow-up were similar. At follow-up, there was no difference in LV ejection fraction (%, median (IQR), (culprit-artery-only PCI vs preventive PCI) 51.7 (42.9, 60.2) vs 54.4 (49.3, 62.8), p=0.23), LV end-diastolic volume (mL/m2, 69.3 (59.4, 79.9) vs 66.1 (54.7, 73.7), p=0.48) and LV end-systolic volume (mL/m2, 31.8 (24.4, 43.0) vs 30.7 (23.0, 36.3), p=0.20). Non-culprit angiographic lesions had low-risk Syntax scores and 47% had non-complex characteristics. Conclusions: Compared with culprit-only PCI, non-infarct-artery MI in the preventive PCI strategy was uncommon and LV volumes and ejection fraction were similar

    Too Many Choices Confuse Patients With Dementia

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    Choices are often difficult to make by patients with Alzheimer Dementia. They often become acutely confused when faced with too many options because they are not able to retain in their working memory enough information about the various individual choices available. In this case study, we describe how an essentially simple benign task (choosing a dress to wear) can rapidly escalate and result in a catastrophic outcome. We examine what went wrong in the patient/caregiver interaction and how that potentially catastrophic situation could have been avoided or defused
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