1,263 research outputs found
On groups and counter automata
We study finitely generated groups whose word problems are accepted by
counter automata. We show that a group has word problem accepted by a blind
n-counter automaton in the sense of Greibach if and only if it is virtually
free abelian of rank n; this result, which answers a question of Gilman, is in
a very precise sense an abelian analogue of the Muller-Schupp theorem. More
generally, if G is a virtually abelian group then every group with word problem
recognised by a G-automaton is virtually abelian with growth class bounded
above by the growth class of G. We consider also other types of counter
automata.Comment: 18 page
The TIGRE gamma-ray telescope
TIGRE is an advanced telescope for gamma-ray astronomy with a few arcmin resolution. From 0.3 to 10 MeV it is a Compton telescope. Above 1 MeV, its multi-layers of double sided silicon strip detectors allow for Compton recoil electron tracking and the unique determination for incident photon direction. From 10 to 100 MeV the tracking feature is utilized for gamma-ray pair event reconstruction. Here we present TIGRE energy resolutions, background simulations and the development of the electronics readout system
ORFEUS-II Far-Ultraviolet Observations of 3C273: 1. Interstellar and Intergalactic Absorption Lines
We present the first intermediate-resolution (lambda / 3000) spectrum of the
bright quasi-stellar object 3C273 at wavelengths between 900 and 1200 A.
Observations were performed with the Berkeley spectrograph aboard the
ORFEUS-SPAS II mission. We detect Lyman beta counterparts to
previously-identified intergalactic Lyman-alpha features at cz = 19900, 1600,
and 1000 km/s; counterparts to other putative Lyman-alpha clouds along the
sight line are below our detection limit. The strengths of the two very low
redshift Lyman-beta features, which are believed to arise in Virgo intracluster
gas, exceed preflight expectations, suggesting that the previous determination
of the cloud parameters may underestimate the true column densities. A
curve-of-growth analysis sets a minimum H I column density of 4 E14/cm^2 for
the 1600 km/s cloud. We find marginally significant evidence for Galactic H_2
along the sight line, with a total column density of about 1 E15/cm^2. We
detect the stronger interstellar O VI doublet member unambiguously; the weaker
member is blended with other features. If the Doppler b value for O VI is
comparable to that determined for N V then the O VI column density is 7 +/- 2
E14/cm^2, significantly above the only previous estimate. The O VI / N V ratio
is about 10, consistent with the low end of the range observed in the disk.
Additional interstellar species detected for the first time toward 3C273 (at
modest statistical significance) include P II, Fe III, Ar I, and S III.Comment: LaTeX file, 11 pages, 4 encapsulated PostScript figures. Uses
aaspp4.sty and astrobib.sty. (Astrobib is available from
http://www.stsci.edu/software/TeX.html .) The ORFEUS telescope is described
at http://sag-www.ssl.berkeley.edu/orfeus/ . To appear in ApJ (Letters
The IL6-like Cytokine Family: Role and Biomarker Potential in Breast Cancer
IL6-like cytokines are a family of regulators with a complex, pleiotropic role in both the healthy organism, where they regulate immunity and homeostasis, and in different diseases, including cancer. Here we summarise how these cytokines exert their effect through the shared signal transducer IL6ST (gp130) and we review the extensive evidence on the role that different members of this family play in breast cancer. Additionally, we discuss how the different cytokines, their related receptors and downstream effectors, as well as specific polymorphisms in these molecules, can serve as predictive or prognostic biomarkers with the potential for clinical application in breast cancer. Lastly, we also discuss how our increasing understanding of this complex signalling axis presents promising opportunities for the development or repurposing of therapeutic strategies against cancer and, specifically, breast neoplasms
Evolution of the canonical sex chromosomes of the guppy and its relatives
The sex chromosomes of the guppy, Poecilia reticulata, and its close relatives are of particular interest: they are much younger than the highly degenerate sex chromosomes of model systems such as humans and Drosophila melanogaster, and they carry many of the genes responsible for the malesâ dramatic coloration. Over the last decade, several studies have analyzed these sex chromosomes using a variety of approaches including sequencing genomes and transcriptomes, cytology, and linkage mapping. Conflicting conclusions have emerged, in particular concerning the history of the sex chromosomes and the evolution of suppressed recombination between the X and Y. Here, we address these controversies by reviewing the evidence and reanalyzing data. We find no evidence of a nonrecombining sex-determining region or evolutionary strata in P. reticulata. Furthermore, we find that the data most strongly support the hypothesis that the sex-determining regions of 2 close relatives of the guppy, Poecilia wingei and Micropoecilia picta, evolved independently after their lineages diverged. We identify possible causes of conflicting results in previous studies and suggest best practices going forward
Comparison of Type II Endoleak Embolizations: Embolization of Endoleak Nidus Only versus Embolization of Endoleak Nidus and Branch Vessels
AbstractPurposeTo compare outcomes of type II endoleak embolization involving embolization of the endoleak nidus only vs embolization of the endoleak nidus and branch vessels in patients treated with endovascular repair of abdominal aortic aneurysms.Materials and MethodsTwenty-nine consecutive patients (mean age, 77.9 y; range, 63â88 y) with type II endoleak who underwent embolization from 2004 to 2015 were retrospectively reviewed. Patients were divided into 2 groups: embolization of endoleak nidus only (group A) and embolization of endoleak nidus and branch vessels (group B). Mean follow-up intervals were 20.5 months ± 14.7 in group A and 24.3 months ± 18.5 in group B. Outcomes were compared between groups by MannâWhitney U and Pearson Ï2 tests.ResultsMean interval from endovascular aneurysm repair to embolization was 47.6 months ± 42.9, and mean presentation time of endoleak before embolization was 23.1 months ± 25.8. Coils (n = 28) and liquid embolic agents (n = 23) were used for embolization. There were no significant differences in rates of residual endoleak (50% vs 53.8%; P = .96) or sac decrease/stabilization (62.5% vs 61.5%; P = .64). Procedure time and radiation exposure in group B (132.3 min ± 78.1; 232.4 Gy·cm2 ± 130.7) were greater than in group A (63.4 min ± 11.9; 61.5 Gy·cm2 ± 35.5; P < .01). There were no procedure-related complications.ConclusionsEmbolization of the endoleak nidus and branch vessels is not superior to embolization of only the nidus in terms of occlusion of type II endoleak and change in sac size despite requiring longer procedure times and resulting in greater patient radiation exposure
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HYDRAULIC AND PHYSICAL PROPERTIES OF SALTSTONE GROUTS AND VAULT CONCRETES
The Saltstone Disposal Facility (SDF), located in the Z-Area of the Savannah River Site (SRS), is used for the disposal of low-level radioactive salt solution. The SDF currently contains two vaults: Vault 1 (6 cells) and Vault 4 (12 cells). Additional disposal cells are currently in the design phase. The individual cells of the saltstone facility are filled with saltstone. Saltstone is produced by mixing the low-level radioactive salt solution, with blast furnace slag, fly ash, and cement (dry premix) to form a dense, micro-porous, monolithic, low-level radioactive waste form. The saltstone is pumped into the disposal cells where it subsequently solidifies. Significant effort has been undertaken to accurately model the movement of water and contaminants through the facility. Key to this effort is an accurate understanding of the hydraulic and physical properties of the solidified saltstone. To date, limited testing has been conducted to characterize the saltstone. The primary focus of this task was to estimate the hydraulic and physical properties of three types of saltstone and two vault concretes. The saltstone formulations included saltstone premix batched with (1) Deliquification, Dissolution, and Adjustment (DDA) salt simulant (w/pm 0.60), (2) Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) salt simulant (w/pm 0.60), and (3) Salt Waste Processing Facility (SWPF) salt simulant (w/pm 0.60). The vault concrete formulations tested included the Vault 1/4 concrete and two variations of the Vault 2 concrete (Mix 1 and Mix 2). Wet properties measured for the saltstone formulations included yield stress, plastic viscosity, wet unit weight, bleed water volume, gel time, set time, and heat of hydration. Hydraulic and physical properties measured on the cured saltstone and concrete samples included saturated hydraulic conductivity, moisture retention, compressive strength, porosity, particle density, and dry bulk density. These properties were determined following a minimum 28 day curing period. Additional testing of the three saltstone formulations was conducted following a minimum 90 day curing period. The compressive strength of each saltstone and concrete material was measured at approximately 14, 28, 56, and 90 days. Recommended hydraulic property values for each saltstone grout and the vault concretes are provided. The hydraulic properties provided for each material include the saturated hydraulic conductivity, dry bulk density, particle density, and porosity. In addition, water retention data are presented for each material along with the van Genuchten transport parameters as determined using the RETC code
Measuring Practicing Cliniciansâ Information Literacy: An Exploratory Analysis in the Context of Panel Management
BACKGROUND:
As healthcare moves towards technology-driven population health management, clinicians must adopt complex digital platforms to access health information and document care.
OBJECTIVES:
This study explored information literacy, a set of skills required to effectively navigate population health information systems, among primary care providers in one Veterans' Affairs (VA) medical center.
METHODS:
Information literacy was assessed during an 8-month randomized trial that tested a population health (panel) management intervention. Providers were asked about their use and comfort with two VA digital tools for panel management at baseline, 16 weeks, and post-intervention. An 8-item scale (range 0-40) was used to measure information literacy (Cronbach's α=0.84). Scores between study arms and provider types were compared using paired t-tests and ANOVAs. Associations between self-reported digital tool use and information literacy were measured via Pearson's correlations.
RESULTS:
Providers showed moderate levels of information literacy (M= 27.4, SD 6.5). There were no significant differences in mean information literacy between physicians (M=26.4, SD 6.7) and nurses (M=30.5, SD 5.2, p=0.57 for difference), or between intervention (M=28.4, SD 6.5) and control groups (M=25.1, SD 6.2, p=0.12 for difference). Information literacy was correlated with higher rates of self-reported information system usage (r=0.547, p=0.001). Clinicians identified data access, accuracy, and interpretability as potential information literacy barriers.
CONCLUSIONS:
While exploratory in nature, cautioning generalizability, the study suggests that measuring and improving clinicians' information literacy may play a significant role in the implementation and use of digital information tools, as these tools are rapidly being deployed to enhance communication among care teams, improve health care outcomes, and reduce overall costs
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