A Multipurpose MRI phantom based on a reverse Micelle solution

Magnetic resonance imaging (MRI) phantoms are anthroprogenic objects used for system performance testing of an MR imager. Current phantoms used today contain aqueous solutions of paramagnetic salts. When imaged, these phantoms produce a standing wave artifact. The presence of this artifact make it difficult to distinguish between inhomogeneities in the B] transmit and receive field of an imaging coil and the imaging phantom. This thesis describes a reverse micelle (RM) solution and its applicability for use in an MR imaging phantom. The RM solution consists of three components: H20, which is surrounded by the surfactant, AOT, to form a droplet, which is suspended in the hydrocarbon, and decane. Volume fractions () of water and AOT from 0.50 to 0.9 0 were studied. The RM solution is easy to make up and is homogeneous. The RM solution was found to be phase-stable at temperatures ranging from 0 to 40C at certain values. The dielectric constant of the RM solution was half the dielectric constant of H20. The resistivity of the RM solution was 5 times greater than an aqueous solution of 6 mM NiCl and 0. 1 54 mM NaCl. The diffusion coefficient of the H20 and AOT component increased as increased. The diffusion coefficient of decane decreased as increased. The viscosity of the RM solution increased as increased. The viscosity of the RM solution is 35 times greater than the viscosity of H20. The RM solutions containing 0. 10, 0.25, and 0.50 mM Mn+2 in the aqueous phase produce overall T and T2 values similar to human tissue. The addition of either 3, 5, or 8 mM Ni+2 in the aqueous phase of the RM solution produces T and T2 values useful for system performance testing. The RM solution containing 8 mM Ni+2 in the aqueous phase displayed the least temperature dependent T] and T2of all six RM solutions studied. The RM solution phantom is effective in B1T and B]R field mapping. An image of the RM solution phantom displays minimal standing wave artifact and no skin-effect artifact. The spectrum of the RM solution phantom contains two peaks which correspond to the fat and H20 spectral peaks of human tissue. Consequently, the RM solution phantom could be used to test the fat saturation imaging sequence. Spectral T values of the H20 and decane component were measured. The individual T values differed from the overall T, values of the RM solution, thus, studying the effects of magnetization transfer between the three components could be possible. *Refer to content file for correct numerical representation

Enhanced climate instability in the North Atlantic and southern Europe during the Last Interglacial.

Considerable ambiguity remains over the extent and nature of millennial/centennial-scale climate instability during the Last Interglacial (LIG). Here we analyse marine and terrestrial proxies from a deep-sea sediment sequence on the Portuguese Margin and combine results with an intensively dated Italian speleothem record and climate-model experiments. The strongest expression of climate variability occurred during the transitions into and out of the LIG. Our records also document a series of multi-centennial intra-interglacial arid events in southern Europe, coherent with cold water-mass expansions in the North Atlantic. The spatial and temporal fingerprints of these changes indicate a reorganization of ocean surface circulation, consistent with low-intensity disruptions of the Atlantic meridional overturning circulation (AMOC). The amplitude of this LIG variability is greater than that observed in Holocene records. Episodic Greenland ice melt and runoff as a result of excess warmth may have contributed to AMOC weakening and increased climate instability throughout the LIG

Contribution of the land sector to a 1.5 °C world

Acknowledgements The analysis in this study was guided by the valuable feedback and recommendations of expert consultations and interviews, and we extend our gratitude to all those individuals who contributed to our research and analysis: Jeff Atkins (Virginia Commonwealth University), Jonah Busch (Earth Innovation Institute), Peter Ellis (The Nature Conservancy), Jason Funk (Center for Carbon Removal), Trisha Gopalakrishna (The Nature Conservancy), Alan Kroeger (Climate Focus), Bernice Lee (Chatham House), Donna Lee (Climate and Land Use Alliance), Simon Lewis (University College London), Guy Lomax (The Nature Conservancy), Dann Mitchell (University of Bristol), Raoni Rajão (University of Minas Gerais), Joeri Rogelj (IIASA), Carl-Friedrich Schleussner (Climate Analytics), Paul West (University of Minnesota), Graham Wynne (Prince of Wales International Sustainability Unit), Ana Yang (Children’s Investment Fund Foundation) and Dan Zarin (Climate and Land Use Alliance). A special thank you to Esther Chak and Mary-Jo Valentino (Imaginary Office) for designing the figures in this study. This work was generously supported by the Children’s Investment Fund Foundation and the authors’ institutions and funding sources.Peer reviewedPostprin

Enzymology of the branched-chain amino acid oxidation disorders: the valine pathway

Valine is one of the three branched-chain amino acids which undergoes oxidation within mitochondria. In this paper, we describe the current state of knowledge with respect to the enzymology of the valine oxidation pathway and the different disorders affecting oxidation

The effectiveness of interventions to change six health behaviours: a review of reviews

Background: Several World Health Organisation reports over recent years have highlighted the high incidence of chronic diseases such as diabetes, coronary heart disease and cancer. Contributory factors include unhealthy diets, alcohol and tobacco use and sedentary lifestyles. This paper reports the findings of a review of reviews of behavioural change interventions to reduce unhealthy behaviours or promote healthy behaviours. We included six different health-related behaviours in the review: healthy eating, physical exercise, smoking, alcohol misuse, sexual risk taking (in young people) and illicit drug use. We excluded reviews which focussed on pharmacological treatments or those which required intensive treatments (e. g. for drug or alcohol dependency). Methods: The Cochrane Library, Database of Abstracts of Reviews of Effectiveness (DARE) and several Ovid databases were searched for systematic reviews of interventions for the six behaviours (updated search 2008). Two reviewers applied the inclusion criteria, extracted data and assessed the quality of the reviews. The results were discussed in a narrative synthesis. Results: We included 103 reviews published between 1995 and 2008. The focus of interventions varied, but those targeting specific individuals were generally designed to change an existing behaviour (e. g. cigarette smoking, alcohol misuse), whilst those aimed at the general population or groups such as school children were designed to promote positive behaviours (e. g. healthy eating). Almost 50% (n = 48) of the reviews focussed on smoking (either prevention or cessation). Interventions that were most effective across a range of health behaviours included physician advice or individual counselling, and workplace- and school-based activities. Mass media campaigns and legislative interventions also showed small to moderate effects in changing health behaviours. Generally, the evidence related to short-term effects rather than sustained/longer-term impact and there was a relative lack of evidence on how best to address inequalities. Conclusions: Despite limitations of the review of reviews approach, it is encouraging that there are interventions that are effective in achieving behavioural change. Further emphasis in both primary studies and secondary analysis (e.g. systematic reviews) should be placed on assessing the differential effectiveness of interventions across different population subgroups to ensure that health inequalities are addressed.</p

The SDSS-III Baryon Oscillation Spectroscopic Survey: Quasar Target Selection for Data Release Nine

The SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), a five-year spectroscopic survey of 10,000 deg^2, achieved first light in late 2009. One of the key goals of BOSS is to measure the signature of baryon acoustic oscillations in the distribution of Ly-alpha absorption from the spectra of a sample of ~150,000 z>2.2 quasars. Along with measuring the angular diameter distance at z\approx2.5, BOSS will provide the first direct measurement of the expansion rate of the Universe at z > 2. One of the biggest challenges in achieving this goal is an efficient target selection algorithm for quasars over 2.2 < z < 3.5, where their colors overlap those of stars. During the first year of the BOSS survey, quasar target selection methods were developed and tested to meet the requirement of delivering at least 15 quasars deg^-2 in this redshift range, out of 40 targets deg^-2. To achieve these surface densities, the magnitude limit of the quasar targets was set at g <= 22.0 or r<=21.85. While detection of the BAO signature in the Ly-alpha absorption in quasar spectra does not require a uniform target selection, many other astrophysical studies do. We therefore defined a uniformly-selected subsample of 20 targets deg^-2, for which the selection efficiency is just over 50%. This "CORE" subsample will be fixed for Years Two through Five of the survey. In this paper we describe the evolution and implementation of the BOSS quasar target selection algorithms during the first two years of BOSS operations. We analyze the spectra obtained during the first year. 11,263 new z>2.2 quasars were spectroscopically confirmed by BOSS. Our current algorithms select an average of 15 z > 2.2 quasars deg^-2 from 40 targets deg^-2 using single-epoch SDSS imaging. Multi-epoch optical data and data at other wavelengths can further improve the efficiency and completeness of BOSS quasar target selection. [Abridged]Comment: 33 pages, 26 figures, 12 tables and a whole bunch of quasars. Submitted to Ap

Expressions 1998-1999

https://openspace.dmacc.edu/expressions/1018/thumbnail.jp

Asymmetric thinning of the cerebral cortex across the adult lifespan is accelerated in Alzheimer’s disease

© 2021, The Author(s). Aging and Alzheimer’s disease (AD) are associated with progressive brain disorganization. Although structural asymmetry is an organizing feature of the cerebral cortex it is unknown whether continuous age- and AD-related cortical degradation alters cortical asymmetry. Here, in multiple longitudinal adult lifespan cohorts we show that higher-order cortical regions exhibiting pronounced asymmetry at age ~20 also show progressive asymmetry-loss across the adult lifespan. Hence, accelerated thinning of the (previously) thicker homotopic hemisphere is a feature of aging. This organizational principle showed high consistency across cohorts in the Lifebrain consortium, and both the topological patterns and temporal dynamics of asymmetry-loss were markedly similar across replicating samples. Asymmetry-change was further accelerated in AD. Results suggest a system-wide dedifferentiation of the adaptive asymmetric organization of heteromodal cortex in aging and AD

Identification of MYC as an antinecroptotic protein that stifles RIPK1-RIPK3 complex formation

The underlying mechanism of necroptosis in relation to cancer is still unclear. Here, MYC, a potent oncogene, is an antinecroptotic factor that directly suppresses the formation of the RIPK1-RIPK3 complex. Gene set enrichment analyses reveal that the MYC pathway is the most prominently down-regulated signaling pathway during necroptosis. Depletion or deletion of MYC promotes the RIPK1-RIPK3 interaction, thereby stabilizing the RIPK1 and RIPK3 proteins and facilitating necroptosis. Interestingly, MYC binds to RIPK3 in the cytoplasm and inhibits the interaction between RIPK1 and RIPK3 in vitro. Furthermore, MYC-nick, a truncated form that is mainly localized in the cytoplasm, prevented TNF-induced necroptosis. Finally, down-regulation of MYC enhances necroptosis in leukemia cells and suppresses tumor growth in a xenograft model upon treatment with birinapant and emricasan. MYC-mediated suppression of necroptosis is a mechanism of necroptosis resistance in cancer, and approaches targeting MYC to induce necroptosis represent an attractive therapeutic strategy for cancer