409 research outputs found
Near Horizon Limits of Massless BTZ and Their CFT Duals
We consider the massless BTZ black hole and show that it is possible to take
its "near horizon" limit in two distinct ways. The first one leads to a null
self-dual orbifold of AdS3 and the second to a spacelike singular AdS3/Z_K
orbifold in the large K limit, the "pinching orbifold". We show that from the
dual 2d CFT viewpoint, the null orbifold corresponds to the p^+=0 sector of the
Discrete Light-Cone Quantisation (DLCQ) of the 2d CFT where a chiral sector of
the CFT is decoupled, while the pinching orbifold corresponds to taking an
infinite mass gap limit in both the right and left sectors of the 2d CFT,
essentially leaving us with the states L_0=\bar L_0=c/24 only. In the latter
case, one can combine the near horizon limit with sending the 3d Planck length
l_P to zero, or equivalently the dual CFT central charge c to infinity. We
provide preliminary evidence that in that case some nontrivial dynamics may
survive the limit.Comment: 22 pages, no figures, v2: minor improvements, references adde
Democracy, development and the executive presidency in Sri Lanka
This paper examines the developmental causes and consequences of the shift from a parliamentary to a semi-presidential system in Sri Lanka in 1978, examining its provenance, rationale, and its unfolding trajectory. drawing on a wide range of sources, it set out an argument that the executive presidency was born out of an elite impulse to create a more stable, centralised political structure to resist the welfarist electoral pressures that had taken hold in the post-independence period, and to pursue a market-driven model of economic growth. This strategy succeeded in its early years 197801993, when presidents retained legislative control, maintained a strong personal commitment to market reforms, and cultivated alternative sources of legitimacy. In the absence of these factors, the presidency slipped into crisis over 1994-2004 as resistance to elite-led projects of state reform mounted and as the president lost control of the legislature. Since 2005 the presidency has regained its power, but at the cost of abandoning its original rationale and function as a means to recalibrate the elite/mass power relations to facilitate elite-led reform agendas
No-Boundary Thinking in Bioinformatics Research
Currently there are definitions from many agencies and research societies defining bioinformatics as deriving knowledge from computational analysis of large volumes of biological and biomedical data. Should this be the bioinformatics research focus? We will discuss this issue in this review article. We would like to promote the idea of supporting human-infrastructure (HI) with no-boundary thinking (NT) in bioinformatics (HINT)
Association of HIV viral load with monocyte chemoattractant protein-1 and atherosclerosis burden measured by magnetic resonance imaging
BACKGROUND: HIV-infected individuals may be at increased risk for atherosclerosis. Although this is partially attributable to metabolic factors, HIV-associated inflammation may play a role.
OBJECTIVE: To investigate associations of HIV disease with serum monocyte chemoattractant protein-1/chemokine (C-C motif) ligand 2 (MCP-1/CCL2) levels and atherosclerosis burden.
DESIGN: A cross-sectional analysis.
METHODS: : Serum MCP-1/CCL2, fasting lipids, and glucose tolerance were measured in 98 HIV-infected and 79 demographically similar uninfected adults. Eighty-four participants had MRI of the carotid arteries and thoracic aorta to measure atherosclerosis burden. Multivariate analyses were performed using linear regression.
RESULTS: Mean MCP-1/CCL2 levels did not differ between HIV-infected and uninfected participants (P = 0.65). Among HIV-infected participants, after adjusting for age, BMI, and cigarette smoking, HIV-1 viral load was positively associated with MCP-1/CCL2 (P = 0.02). Multivariate analyses adjusting for sex, low-density lipoprotein cholesterol, total cholesterol:high-density lipoprotein cholesterol ratio, cigarette smoking, MCP-1/CCL2, and protease inhibitor use found that HIV infection was associated with greater mean thoracic aorta vessel wall area (VWA, P < 0.01) and vessel wall thickness (VWT, P = 0.03), but not with carotid artery parameters. Compared with being uninfected, having detectable HIV-1 viremia was associated with greater mean thoracic aorta VWA (P < 0.01) and VWT (P = 0.03), whereas being HIV-infected with undetectable viral load was associated with greater thoracic aorta VWA (P = 0.02) but not VWT (P = 0.15). There was an independent positive association of MCP-1/CCL2 with thoracic aorta VWA (P = 0.01) and VWT (P = 0.01).
CONCLUSION: HIV-1 viral burden is associated with higher serum levels of MCP-1/CCL2 and with atherosclerosis burden, as assessed by thoracic aorta VWA and VWT
Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas
This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing
molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin
Pan-Cancer Analysis of lncRNA Regulation Supports Their Targeting of Cancer Genes in Each Tumor Context
Long noncoding RNAs (lncRNAs) are commonly dys-regulated in tumors, but only a handful are known toplay pathophysiological roles in cancer. We inferredlncRNAs that dysregulate cancer pathways, onco-genes, and tumor suppressors (cancer genes) bymodeling their effects on the activity of transcriptionfactors, RNA-binding proteins, and microRNAs in5,185 TCGA tumors and 1,019 ENCODE assays.Our predictions included hundreds of candidateonco- and tumor-suppressor lncRNAs (cancerlncRNAs) whose somatic alterations account for thedysregulation of dozens of cancer genes and path-ways in each of 14 tumor contexts. To demonstrateproof of concept, we showed that perturbations tar-geting OIP5-AS1 (an inferred tumor suppressor) andTUG1 and WT1-AS (inferred onco-lncRNAs) dysre-gulated cancer genes and altered proliferation ofbreast and gynecologic cancer cells. Our analysis in-dicates that, although most lncRNAs are dysregu-lated in a tumor-specific manner, some, includingOIP5-AS1, TUG1, NEAT1, MEG3, and TSIX, synergis-tically dysregulate cancer pathways in multiple tumorcontexts
Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas
Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN
Spatial Organization and Molecular Correlation of Tumor-Infiltrating Lymphocytes Using Deep Learning on Pathology Images
Beyond sample curation and basic pathologic characterization, the digitized H&E-stained images
of TCGA samples remain underutilized. To highlight this resource, we present mappings of tumorinfiltrating lymphocytes (TILs) based on H&E images from 13 TCGA tumor types. These TIL
maps are derived through computational staining using a convolutional neural network trained to
classify patches of images. Affinity propagation revealed local spatial structure in TIL patterns and
correlation with overall survival. TIL map structural patterns were grouped using standard
histopathological parameters. These patterns are enriched in particular T cell subpopulations
derived from molecular measures. TIL densities and spatial structure were differentially enriched
among tumor types, immune subtypes, and tumor molecular subtypes, implying that spatial
infiltrate state could reflect particular tumor cell aberration states. Obtaining spatial lymphocytic
patterns linked to the rich genomic characterization of TCGA samples demonstrates one use for
the TCGA image archives with insights into the tumor-immune microenvironment
Hematological Changes as Prognostic Indicators of Survival: Similarities Between Gottingen Minipigs, Humans, and Other Large Animal Models
The animal efficacy rule addressing development of drugs for selected disease categories has pointed out the need to develop alternative large animal models. Based on this rule, the pathophysiology of the disease in the animal model must be well characterized and must reflect that in humans. So far, manifestations of the acute radiation syndrome (ARS) have been extensively studied only in two large animal models, the non-human primate (NHP) and the canine. We are evaluating the suitability of the minipig as an additional large animal model for development of radiation countermeasures. We have previously shown that the Gottingen minipig manifests hematopoietic ARS phases and symptoms similar to those observed in canines, NHPs, and humans.We establish here the LD50/30 dose (radiation dose at which 50% of the animals succumb within 30 days), and show that at this dose the time of nadir and the duration of cytopenia resemble those observed for NHP and canines, and mimic closely the kinetics of blood cell depletion and recovery in human patients with reversible hematopoietic damage (H3 category, METREPOL approach). No signs of GI damage in terms of diarrhea or shortening of villi were observed at doses up to 1.9 Gy. Platelet counts at days 10 and 14, number of days to reach critical platelet values, duration of thrombocytopenia, neutrophil stress response at 3 hours and count at 14 days, and CRP-to-platelet ratio were correlated with survival. The ratios between neutrophils, lymphocytes and platelets were significantly correlated with exposure to irradiation at different time intervals.As a non-rodent animal model, the minipig offers a useful alternative to NHP and canines, with attractive features including ARS resembling human ARS, cost, and regulatory acceptability. Use of the minipig may allow accelerated development of radiation countermeasures
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