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RKKY coupling in Weyl semimetal thin films
No full textWe consider the effective coupling between impurity spins on surfaces of a thin-film Weyl semimetal within Ruderman-Kittel-Kasuya-Yosida (RKKY) theory. If the spins are on the same surface, their coupling reflects the anisotropy and the spin-momentum locking of the Fermi arcs. By contrast when the spins are on opposite surfaces, their coupling is mediated by the Fermi arcs as well as by bulk states. In this case the coupling is both surprisingly strong and highly thickness dependent, with a maximum at an optimum thickness. We demonstrate our results using analytical solutions of states in the thin-film geometry, as well as using a two-surface recursive Green's function analysis of the tight-binding model
Graphicons and Tactics in Satirical Trolling on Tumblr.com
No full textInternet trolling is inherently multimodal, relying on both textual and graphical means of communication (or “graphicons”). We examined how satire and ideological trolls who use graphicons on the microblogging site Tumblr.com, use knowledge of local culture as part of their trolling tactics. Based on a qualitative thematic analysis of 172 trolling posts (that include 284 graphicons), we identified 7 Tumblr satire troll tactics: the lying tactic, the derailment tactic, the parodic exaggeration tactic, the misappropriation of jargon tactic, the straight man (or “comical seriousness”) tactic, the troll reveal tactic, and the politeness tactic. We also found that ideologically extremizing language was the most commonly used outrage tactic and that trolls used graphicons frequently as flame baiting prompts and for tone modification
Methods to Account for Citation Inflation in Research Evaluation
No full textQuantitative research evaluation requires measures that are transparent, relatively simple, and free of dis- ciplinary and temporal bias. We document and provide a solution to a hitherto unaddressed temporal bias – citation inflation – which arises from the basic fact that scientific publication is steadily growing at roughly 4% per year. Moreover, because the total production of citations grows by a factor of 2 every 12 years, this means that the real value of a citation depends on when it was produced. Consequently, failing to convert nominal citation values into real citation values produces significant mis-measurement of scientific impact. To address this problem, we develop a citation deflator method, outline the steps to generalize and implement it using the Web of Science portal, and analyze a large set of researchers from biology and physics to demonstrate how two common evaluation metrics – total citations and h-index – can differ by a remarkable amount depending on whether the underlying citation counts are deflated or not. In particular, our results show that the scientific impact of prior generations is likely to be significantly underestimated when citations are not deflated, often by 100% or more of the nominal value. Thus, our study points to the need for a systemic overhaul of the counting methods used evaluating citation impact – especially in the case of researchers, journals, and institutions – which can span several decades and thus several doubling periods
Identifying vulnerable brain networks in mouse models of genetic risk factors for late onset Alzheimer's disease
No full textThe major genetic risk for late onset Alzheimer’s disease has been associated with the presence of APOE4 alleles. However, the impact of different APOE alleles on the brain aging trajectory, and how they interact with the brain local environment in a sex specific manner is not entirely clear. We sought to identify vulnerable brain circuits in novel mouse models with homozygous targeted replacement of the mouse ApoE gene with either human APOE3 or APOE4 gene alleles. These genes are expressed in mice that also model the human immune response to age and disease-associated challenges by expressing the human NOS2 gene in place of the mouse mNos2 gene. These mice had impaired learning and memory when assessed with the Morris water maze (MWM) and novel object recognition (NOR) tests. Ex vivo MRI-DTI analyses revealed global and local atrophy, and areas of reduced fractional anisotropy (FA). Using tensor network principal component analyses for structural connectomes, we inferred the pairwise connections which best separate APOE4 from APOE3 carriers. These involved primarily interhemispheric connections among regions of olfactory areas, the hippocampus, and the cerebellum. Our results also suggest that pairwise connections may be subdivided and clustered spatially to reveal local changes on a finer scale. These analyses revealed not just genotype, but also sex specific differences. Identifying vulnerable networks may provide targets for interventions, and a means to stratify patients
A Mn-sensing riboswitch activates expression of a Mn2+/Ca2+ ATPase transporter in Streptococcus
No full textMaintaining manganese (Mn) homeostasis is important for the virulence of numerous bacteria. In the human respiratory pathogen , the Mn-specific importer PsaBCA, exporter MntE, and transcriptional regulator PsaR establish Mn homeostasis. In other bacteria, Mn homeostasis is controlled by family riboswitches. Here, we characterize a family riboswitch upstream of the gene encoding a P-type ATPase in , suggested previously to function in Ca efflux. We show that the riboswitch aptamer domain adopts a canonical structure containing a three-way junction that is compacted in the presence of Ca or Mn at a physiological Mg concentration. Although Ca binds to the RNA aptamer with higher affinity than Mn, in vitro activation of transcription read-through of by Mn is much greater than by Ca. Consistent with this result, mRNA and protein levels increase ≈5-fold during cellular Mn stress, but only in genetic backgrounds of and that exhibit Mn sensitivity, revealing that this riboswitch functions as a failsafe ‘on’ signal to prevent Mn toxicity in the presence of high cellular Mn. In addition, our results suggest that the riboswitch functions to regulate Ca efflux under these conditions
Quantifying exposure to running for meaningful insights into running-related injuries
No full textThe very term ‘running-related overuse injury’ implies the importance of ‘use’, or exposure, to running. Risk factors for running-related injury can be better understood when exposure to running is quantified using either external or internal training loads. The advent of objective methods for quantifying exposure to running, such as global positioning system watches, smartphones, commercial activity monitors and research-grade wearable sensors, make it possible for researchers, coaches and clinicians to track exposure to running with unprecedented detail. This viewpoint discusses practical issues surrounding the use and analysis of data from such devices, including how wearable devices can be used to assess both internal and external training loads. We advocate for an integrative approach where data from multiple sources are used in combination to directly measure exposure to running in diverse settings
Detecting white matter alterations in multiple sclerosis using advanced diffusion magnetic resonance imaging
No full textMultiple sclerosis is a neurodegenerative and inflammatory disease, a hallmark of which is demyelinating lesions in the white matter. We hypothesized that alterations in white matter microstructures can be non-invasively characterized by advanced diffusion magnetic resonance imaging. Seven diffusion metrics were extracted from hybrid diffusion imaging acquisitions via classic diffusion tensor imaging, neurite orientation dispersion and density imaging, and q-space imaging. We investigated the sensitivity of the diffusion metrics in 36 sets of regions of interest in the brain white matter of six female patients (age 52.8 ± 4.3 years) with multiple sclerosis. Each region of interest set included a conventional T2-defined lesion, a matched perilesion area, and normal-appearing white matter. Six patients with multiple sclerosis (n = 5) or clinically isolated syndrome (n = 1) at a mild to moderate disability level were recruited. The patients exhibited microstructural alterations from normal-appearing white matter transitioning to perilesion areas and lesions, consistent with decreased tissue restriction, decreased axonal density, and increased classic diffusion tensor imaging diffusivity. The findings suggest that diffusion compartment modeling and q-space analysis appeared to be sensitive for detecting subtle microstructural alterations between perilesion areas and normal-appearing white matter
Sexual frequency and pain in a randomized clinical trial of vaginal estradiol tablets, moisturizer, and placebo in postmenopausal women
No full textObjective: To evaluate the efficacy of two common interventions for bothersome postmenopausal vaginal symptoms on improving sexual frequency and pain. Methods: This is a post-hoc analysis of data from a 12-week double-blind placebo-controlled trial that randomized postmenopausal women (ages 45–70 years) with moderate-severe genitourinary discomfort to vaginal 10mcg estradiol tablet plus placebo gel (n=102), placebo tablet plus vaginal moisturizer (n=100), or dual placebo (n=100). Outcomes were proportion of sexually active women at 12 weeks, frequency of sexual activity, and pain severity with sexual activity (0–3 scale). Consistent with the original study design, comparisons were made between each active arm and the dual placebo arm. Results: Most women enrolled in the trial, 294/302 (97%), had sufficient data to be included in this analysis. Mean age of participants was 61 years, most were white (88%), college educated (66%), and most reported sexual activity in the month prior to enrollment (81%). After 12 weeks of treatment, a similar proportion of women in the vaginal estrogen and dual placebo groups reported sexual activity in the past week (50% and 40%; p=0.10) and the past month (78% and 84%, p=0.52). Mean (SD) pain with sexual activity scores at 12 weeks were similar between vaginal estrogen [1.0 (1.0)] and placebo [0.9 (0.9), p=0.52] groups. The proportion sexually active at 12 weeks (35%) and mean (SD) pain severity in the vaginal moisturizer group [1.1 (0.9)] did not differ from placebo (p=0.36). Conclusions: Compared to placebo, neither low dose vaginal estradiol nor vaginal moisturizer treatment over 12 weeks resulted in significantly greater increases in the proportions of women reporting sexual activity or improvement in pain scores with sexual activity
Physical activity and weight gain after smoking cessation in postmenopausal women.
No full textObjective Weight gain frequently occurs following smoking cessation. The objective of this study was to examine whether weight gain after smoking cessation was attenuated by PA in postmenopausal women. Methods 4717 baseline smokers from the Women’s Health Initiative (WHI) were followed for three years. 1282 women quit smoking, and 3435 continued smoking. Weight was measured at baseline and at the year 3 visit. PA was assessed at both times by self-report, summarized as metabolic equivalent task (MET)-hours per week. Multiple linear regression models were used to assess the association between PA and post-cessation weight gain, adjusting for potential confounding factors. Results Compared with continuing smokers, quitters gained an average of 3.5 kg (SD=5.6) between the baseline and year 3 visit. Quitters with decreased PA had the highest amount of weight gain (3.88 kg, 95% CI: 3.22-4.54); quitters with increased PA (≥15 MET-hours/week) had the lowest weight gain (2.55 kg, 95% CI: 1.59-3.52). Increased PA had a stronger beneficial association for post-cessation weight gain for obese women compared to normal weight women. Quitters who had low PA at baseline and high PA at year 3 and were also enrolled in a dietary modification intervention had non-significant weight gain (1.88 kg, 95% CI: −0.21-3.96) compared with continuing smokers. Conclusions Our data demonstrate that even a modest increase in PA (equivalent to current recommendations) can attenuate weight gain after quitting smoking among postmenopausal women, especially in combination with improved diet
Fame and Fortune: Developing a Simulation Game for the Music Industry Classroom
No full textThis study documents the development of a classroom game simulating the effects of contractual arrangements on the economic relationships between artists, record labels, and consumers. The game was tested with multiple revisions in classroom settings over a period of three years by using surveys, interviews, session videos, and teacher observations. Using the approach of Grounded Theory, observations and insights were extracted from the collected data with the goal of identifying effective strategies for developing and using classroom simulations. Findings include evidence of deeper engagement with the subject through cognitive, psychomotor, and affective learning