Current-Induced Effective Magnetic Fields in Co/Cu/Co Nanopillars

We present a method to measure the effective field contribution to spin-transfer-induced interactions between the magnetic layers in a trilayer nanostructure, which enables spin-current effects to be distinguished from the usual charge-current-induced magnetic fields. This technique is demonstrated on submicron Co/Cu/Co nanopillars. The hysteresis loop of one of the magnetic layers in the trilayer is measured as a function of current while the direction of magnetization of the other layer is kept fixed, first in one direction and then in the opposite direction. These measurements show a current-dependent shift of the hysteresis loop which, based on the symmetry of the magnetic response, we associate with spin-transfer. The observed loop-shift with applied current at room temperature is reduced in measurements at 4.2 K. We interprete these results both in terms of a spin-current dependent effective activation barrier for magnetization reversal and a spin-current dependent effective magnetic field. From data at 4.2 K we estimate the magnitude of the spin-transfer induced effective field to be $\sim 1.5 \times 10^{-7}$ Oe cm$^2$/A, about a factor of 5 less than the spin-transfer torque.Comment: 6 pages, 4 figure

Spatial distribution of local currents of massless Dirac fermions in quantum transport through graphene nanoribbons

We employ the formalism of bond currents, expressed in terms of the nonequilibrium Green functions, to image the charge flow between two sites of the honeycomb lattice of graphene ribbons of few nanometers width. In sharp contrast to nonrelativistic electrons, current density profiles of quantum transport at energies close to the Dirac point in clean zigzag graphene nanoribbons (ZGNR) differs markedly from the profiles of charge density peaked at the edges due to zero-energy localized edge states. For transport through the lowest propagating mode induced by these edge states, edge vacancies do not affect current density peaked in the center of ZGNR. The long-range potential of a single impurity acts to reduce local current around it while concurrently increasing the current density along the zigzag edge, so that ZGNR conductance remains perfect $G=2e^2/h$.Comment: 5 pages, 5 figure

Reproducibility in modeling and simulation of the knee:Academic, industry, and regulatory perspectives

Stakeholders in the modeling and simulation (M&amp;S) community organized a workshop at the 2019 Annual Meeting of the Orthopaedic Research Society (ORS) entitled “Reproducibility in Modeling and Simulation of the Knee: Academic, Industry, and Regulatory Perspectives.” The goal was to discuss efforts among these stakeholders to address irreproducibility in M&amp;S focusing on the knee joint. An academic representative from a leading orthopedic hospital in the United States described a multi-institutional, open effort funded by the National Institutes of Health to assess model reproducibility in computational knee biomechanics. A regulatory representative from the United States Food and Drug Administration indicated the necessity of standards for reproducibility to increase utility of M&amp;S in the regulatory setting. An industry representative from a major orthopedic implant company emphasized improving reproducibility by addressing indeterminacy in personalized modeling through sensitivity analyses, thereby enhancing preclinical evaluation of joint replacement technology. Thought leaders in the M&amp;S community stressed the importance of data sharing to minimize duplication of efforts. A survey comprised 103 attendees revealed strong support for the workshop and for increasing emphasis on computational modeling at future ORS meetings. Nearly all survey respondents (97%) considered reproducibility to be an important issue. Almost half of respondents (45%) tried and failed to reproduce the work of others. Two-thirds of respondents (67%) declared that individual laboratories are most responsible for ensuring reproducible research whereas 44% thought that journals are most responsible. Thought leaders and survey respondents emphasized that computational models must be reproducible and credible to advance knee M&amp;S.</p

Serum metabolomic profiling in acute alcoholic hepatitis identifies multiple dysregulated pathways

Background and Objectives While animal studies have implicated derangements of global energy homeostasis in the pathogenesis of acute alcoholic hepatitis (AAH), the relevance of these findings to the development of human AAH remains unclear. Using global, unbiased serum metabolomics analysis, we sought to characterize alterations in metabolic pathways associated with severe AAH and identify potential biomarkers for disease prognosis. Methods This prospective, case-control study design included 25 patients with severe AAH and 25 ambulatory patients with alcoholic cirrhosis. Serum samples were collected within 24 hours of the index clinical encounter. Global, unbiased metabolomics profiling was performed. Patients were followed for 180 days after enrollment to determine survival. Results Levels of 234 biochemicals were altered in subjects with severe AAH. Random-forest analysis, principal component analysis, and integrated hierarchical clustering methods demonstrated that metabolomics profiles separated the two cohorts with 100% accuracy. Severe AAH was associated with enhanced triglyceride lipolysis, impaired mitochondrial fatty acid beta oxidation, and upregulated omega oxidation. Low levels of multiple lysolipids and related metabolites suggested decreased plasma membrane remodeling in severe AAH. While most measured bile acids were increased in severe AAH, low deoxycholate and glycodeoxycholate levels indicated intestinal dysbiosis. Several changes in substrate utilization for energy homeostasis were identified in severe AAH, including increased glucose consumption by the pentose phosphate pathway, altered tricarboxylic acid (TCA) cycle activity, and enhanced peptide catabolism. Finally, altered levels of small molecules related to glutathione metabolism and antioxidant vitamin depletion were observed in patients with severe AAH. Univariable logistic regression revealed 15 metabolites associated with 180-day survival in severe AAH. Conclusion Severe AAH is characterized by a distinct metabolic phenotype spanning multiple pathways. Metabolomics profiling revealed a panel of biomarkers for disease prognosis, and future studies are planned to validate these findings in larger cohorts of patients with severe AAH.This study was funded by Grant 5K08AA017622 from the National Institutes of Health and a University of Pittsburgh Medical Center Pilot Grant to JB. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Early intervention with Bifidobacterium lactis NCC2818 modulates the host-microbe interface independent of the sustained changes induced by the neonatal environment

Inflammatory and metabolic diseases can originate during early-life and have been correlated with shifts in intestinal microbial ecology. Here we demonstrate that minor environmental fluctuations during the early neonatal period had sustained effects on the developing porcine microbiota and host-microbe interface. These inter-replicate effects appear to originate during the first day of life, and are likely to reflect very early microbiota acquisition from the environment. We statistically link early systemic inflammation with later local increases in inflammatory cytokine (IL-17) production, which could have important enteric health implications. Immunity, intestinal barrier function, host metabolism and host-microbiota co-metabolism were further modified by Bifidobacterium lactis NCC2818 supplementation, although composition of the in situ microbiota remained unchanged. Finally, our robust model identified novel, strong correlations between urinary metabolites (eg malonate, phenylacetylglycine, alanine) and mucosal immunoglobulin (IgM) and cytokine (IL-10, IL-4) production, thus providing the possibility of the development of urinary ‘dipstick’ tests to assess non-accessible mucosal immune development and identify early precursors (biomarkers) of disease. These results have important implications for infants exposed to neonatal factors including caesarean delivery, antibiotic therapy and delayed discharge from hospital environments, which may predispose to the development of inflammatory and metabolic diseases in later life

An exploration of influences on women’s birthplace decision-making in New Zealand: a mixed methods prospective cohort within the Evaluating Maternity Units study

BACKGROUND: There is worldwide debate surrounding the safety and appropriateness of different birthplaces for well women. One of the primary objectives of the Evaluating Maternity Units prospective cohort study was to compare the clinical outcomes for well women, intending to give birth in either an obstetric-led tertiary hospital or a free-standing midwifery-led primary maternity unit. This paper addresses a secondary aim of the study – to describe and explore the influences on women’s birthplace decision-making in New Zealand, which has a publicly funded, midwifery-led continuity of care maternity system. METHODS: This mixed method study utilised data from the six week postpartum survey and focus groups undertaken in the Christchurch area in New Zealand (2010–2012). Christchurch has a tertiary hospital and four primary maternity units. The survey was completed by 82% of the 702 study participants, who were well, pregnant women booked to give birth in one of these places. All women received midwifery-led continuity of care, regardless of their intended or actual birthplace. RESULTS: Almost all the respondents perceived themselves as the main birthplace decision-makers. Accessing a ‘specialist facility’ was the most important factor for the tertiary hospital group. The primary unit group identified several factors, including ‘closeness to home’, ‘ease of access’, the ‘atmosphere’ of the unit and avoidance of ‘unnecessary intervention’ as important. Both groups believed their chosen birthplace was the right and ‘safe’ place for them. The concept of ‘safety’ was integral and based on the participants’ differing perception of safety in childbirth. CONCLUSIONS: Birthplace is a profoundly important aspect of women’s experience of childbirth. This is the first published study reporting New Zealand women’s perspectives on their birthplace decision-making. The groups’ responses expressed different ideologies about childbirth. The tertiary hospital group identified with the ‘medical model’ of birth, and the primary unit group identified with the ‘midwifery model’ of birth. Research evidence affirming the ‘clinical safety’ of primary units addresses only one aspect of the beliefs influencing women’s birthplace decision-making. In order for more women to give birth at a primary unit other aspects of women’s beliefs need addressing, and much wider socio-political change is required

Is there a biomedical explanation for socioeconomic differences in incident mobility limitation?

BACKGROUND: The association between low socioeconomic status and poor physical functioning has been well described; biomedical factors may play an important role in explaining these differences. This study examines the association between socioeconomic status and incident mobility limitation in well-functioning older adults, and seeks to determine whether this link could be explained by biomedical factors. METHODS: Data were obtained from 3066 men and women, aged 70--79 years from Pittsburgh, Pennsylvania and Memphis, Tennessee participating in the Health, Aging and Body Composition (Health ABC) study. Three indicators of socioeconomic status were used: education, income, and ownership of financial assets. Mobility limitation was defined as reporting difficulty walking 1/4 mile or climbing 10 steps during two consecutive semiannual assessments over 4.5 years. Biomedical factors included a wide range of diseases (e.g., heart and cerebrovascular disease) and biological risk factors (e.g. hypertension, poor pulmonary function, and high serum levels of inflammatory markers). RESULTS: Adjusted hazard ratios of incident mobility limitation were significantly higher in those persons with low education, low income, and few assets. Hazard ratios ranged from 1.66 to 2.80 in the lowest socioeconomic groups. Additional adjustment for biomedical factors reduced the hazard ratios by an average of 41% for education, 17% for income, and 29% for assets. CONCLUSION: Biomedical factors can account for some of the association between socioeconomic status and incident mobility limitation. However, to reduce physical disabilities and, in particular, the socioeconomic differences therein, it may not be sufficient to solely intervene upon biological risk factors and risks of disease

Dutch guideline on total hip prosthesis

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