Stellar Disk Truncations: Where do we stand ?

In the light of several recent developments we revisit the phenomenon of galactic stellar disk truncations. Even 25 years since the first paper on outer breaks in the radial light profiles of spiral galaxies, their origin is still unclear. The two most promising explanations are that these 'outer edges' either trace the maximum angular momentum during the galaxy formation epoch, or are associated with global star formation thresholds. Depending on their true physical nature, these outer edges may represent an improved size characteristic (e.g., as compared to D_25) and might contain fossil evidence imprinted by the galaxy formation and evolutionary history. We will address several observational aspects of disk truncations: their existence, not only in normal HSB galaxies, but also in LSB and even dwarf galaxies; their detailed shape, not sharp cut-offs as thought before, but in fact demarcating the start of a region with a steeper exponential distribution of starlight; their possible association with bars; as well as problems related to the line-of-sight integration for edge-on galaxies (the main targets for truncation searches so far). Taken together, these observations currently favour the star-formation threshold model, but more work is necessary to implement the truncations as adequate parameters characterising galactic disks.Comment: LaTeX, 10 pages, 6 figures, presented at the "Penetrating Bars through Masks of Cosmic Dust" conference in South Africa, proceedings published by Kluwer, and edited by Block, D.L., Freeman, K.C., Puerari, I., & Groess, R; v3 to match published versio

Scale-invariant structure of size fluctuations in plants

A wide range of physical and biological systems exhibit complex behaviours characterised by a scale-invariant structure of the fluctuations in their output signals. In the context of plant populations, scaling relationships are typically allometric. In this study, we analysed spatial variation in the size of maize plants (Zea Mays L.) grown in agricultural plots at constant densities and found evidence of scaling in the size fluctuations of plants. The findings indicate that the scaling of the probability distribution of spatial size fluctuation exhibits non-Gaussian behaviour compatible with a Lévy stable process. The scaling relationships were observed for spatial scales spanning three orders of magnitude. These findings should provide additional information for the selection and development of empirically accurate models of pattern formation in plant populations

Soluble tumor necrosis factor receptor 1 and 2 predict outcomes in advanced chronic kidney disease : a prospective cohort study

Background : Soluble tumor necrosis factor receptors 1 (sTNFR1) and 2 (sTNFR2) have been associated to progression of renal failure, end stage renal disease and mortality in early stages of chronic kidney disease (CKD), mostly in the context of diabetic nephropathy. The predictive value of these markers in advanced stages of CKD irrespective of the specific causes of kidney disease has not yet been defined. In this study, the relationship between sTNFR1 and sTNFR2 and the risk for adverse cardiovascular events (CVE) and all-cause mortality was investigated in a population with CKD stage 4-5, not yet on dialysis, to minimize the confounding by renal function. Patients and methods : In 131 patients, CKD stage 4-5, sTNFR1, sTNFR2 were analysed for their association to a composite endpoint of all-cause mortality or first non-fatal CVE by univariate and multivariate Cox proportional hazards models. In the multivariate models, age, gender, CRP, eGFR and significant comorbidities were included as covariates. Results : During a median follow-up of 33 months, 40 events (30.5%) occurred of which 29 deaths (22.1%) and 11 (8.4%) first non-fatal CVE. In univariate analysis, the hazard ratios (HR) of sTNFR1 and sTNFR2 for negative outcome were 1.49 (95% confidence interval (CI): 1.28-1.75) and 1.13 (95% CI: 1.06-1.20) respectively. After adjustment for clinical covariables (age, CRP, diabetes and a history of cardiovascular disease) both sTNFRs remained independently associated to outcomes (HR: sTNFR1: 1.51, 95% CI: 1.30-1.77; sTNFR2: 1.13, 95% CI: 1.06-1.20). A subanalysis of the non-diabetic patients in the study population confirmed these findings, especially for sTNFR1. Conclusion : sTNFR1 and sTNFR2 are independently associated to all-cause mortality or an increased risk for cardiovascular events in advanced CKD irrespective of the cause of kidney disease

SILAC-based proteomic quantification of chemoattractant-induced cytoskeleton dynamics on a second to minute timescale

Cytoskeletal dynamics during cell behaviours ranging from endocytosis and exocytosis to cell division and movement is controlled by a complex network of signalling pathways, the full details of which are as yet unresolved. Here we show that SILAC-based proteomic methods can be used to characterize the rapid chemoattractant-induced dynamic changes in the actin–myosin cytoskeleton and regulatory elements on a proteome-wide scale with a second to minute timescale resolution. This approach provides novel insights in the ensemble kinetics of key cytoskeletal constituents and association of known and novel identified binding proteins. We validate the proteomic data by detailed microscopy-based analysis of in vivo translocation dynamics for key signalling factors. This rapid large-scale proteomic approach may be applied to other situations where highly dynamic changes in complex cellular compartments are expected to play a key role

Neutrino Mass, Sneutrino Dark Matter and Signals of Lepton Flavor Violation in the MRSSM

We study the phenomenology of mixed-sneutrino dark matter in the Minimal R-Symmetric Supersymmetric Standard Model (MRSSM). Mixed sneutrinos fit naturally within the MRSSM, as the smallness (or absence) of neutrino Yukawa couplings singles out sneutrino A-terms as the only ones not automatically forbidden by R-symmetry. We perform a study of randomly generated sneutrino mass matrices and find that (i) the measured value of $\Omega_{DM}$ is well within the range of typical values obtained for the relic abundance of the lightest sneutrino, (ii) with small lepton-number-violating mass terms $m_{nn}^{2} {\tilde n} {\tilde n}$ for the right-handed sneutrinos, random matrices satisfying the $\Omega_{DM}$ constraint have a decent probability of satisfying direct detection constraints, and much of the remaining parameter space will be probed by upcoming experiments, (iii) the $m_{nn}^{2} {\tilde n} {\tilde n}$ terms radiatively generate appropriately small Majorana neutrino masses, with neutrino oscillation data favoring a mostly sterile lightest sneutrino with a dominantly mu/tau-flavored active component, and (iv) a sneutrino LSP with a significant mu component can lead to striking signals of e-mu flavor violation in dilepton invariant-mass distributions at the LHC.Comment: Revised collider analysis in Sec. 5 after fixing error in particle spectrum, References adde

Regulation of neutrophil senescence by microRNAs

Neutrophils are rapidly recruited to sites of tissue injury or infection, where they protect against invading pathogens. Neutrophil functions are limited by a process of neutrophil senescence, which renders the cells unable to respond to chemoattractants, carry out respiratory burst, or degranulate. In parallel, aged neutrophils also undergo spontaneous apoptosis, which can be delayed by factors such as GMCSF. This is then followed by their subsequent removal by phagocytic cells such as macrophages, thereby preventing unwanted inflammation and tissue damage. Neutrophils translate mRNA to make new proteins that are important in maintaining functional longevity. We therefore hypothesised that neutrophil functions and lifespan might be regulated by microRNAs expressed within human neutrophils. Total RNA from highly purified neutrophils was prepared and subjected to microarray analysis using the Agilent human miRNA microarray V3. We found human neutrophils expressed a selected repertoire of 148 microRNAs and that 6 of these were significantly upregulated after a period of 4 hours in culture, at a time when the contribution of apoptosis is negligible. A list of predicted targets for these 6 microRNAs was generated from http://mirecords.biolead.org and compared to mRNA species downregulated over time, revealing 83 genes targeted by at least 2 out of the 6 regulated microRNAs. Pathway analysis of genes containing binding sites for these microRNAs identified the following pathways: chemokine and cytokine signalling, Ras pathway, and regulation of the actin cytoskeleton. Our data suggest that microRNAs may play a role in the regulation of neutrophil senescence and further suggest that manipulation of microRNAs might represent an area of future therapeutic interest for the treatment of inflammatory disease

To respond or not to respond - a personal perspective of intestinal tolerance

For many years, the intestine was one of the poor relations of the immunology world, being a realm inhabited mostly by specialists and those interested in unusual phenomena. However, this has changed dramatically in recent years with the realization of how important the microbiota is in shaping immune function throughout the body, and almost every major immunology institution now includes the intestine as an area of interest. One of the most important aspects of the intestinal immune system is how it discriminates carefully between harmless and harmful antigens, in particular, its ability to generate active tolerance to materials such as commensal bacteria and food proteins. This phenomenon has been recognized for more than 100 years, and it is essential for preventing inflammatory disease in the intestine, but its basis remains enigmatic. Here, I discuss the progress that has been made in understanding oral tolerance during my 40 years in the field and highlight the topics that will be the focus of future research

A Model of Proto-Anti-Codon RNA Enzymes Requiring l-Amino Acid Homochirality

All living organisms encode the 20 natural amino acid units of polypeptides using a universal scheme of triplet nucleotide “codons”. Disparate features of this codon scheme are potentially informative of early molecular evolution: (i) the absence of any codons for d-amino acids; (ii) the odd combination of alternate codon patterns for some amino acids; (iii) the confinement of synonymous positions to a codon’s third nucleotide; (iv) the use of 20 specific amino acids rather than a number closer to the full coding potential of 64; and (v) the evolutionary relationship of patterns in stop codons to amino acid codons. Here I propose a model for an ancestral proto-anti-codon RNA (pacRNA) auto-aminoacylation system and show that pacRNAs would naturally manifest features of the codon table. I show that pacRNAs could implement all the steps for auto-aminoacylation: amino acid coordination, intermediate activation of the amino acid by the 5′-end of the pacRNA, and 3′-aminoacylation of the pacRNA. The anti-codon cradles of pacRNAs would have been able to recognize and coordinate only a small number of l-amino acids via hydrogen bonding. A need for proper spatial coordination would have limited the number of chargeable amino acids for all anti-codon sequences, in addition to making some anti-codon sequences unsuitable. Thus, the pacRNA model implies that the idiosyncrasies of the anti-codon table and l-amino acid homochirality co-evolved during a single evolutionary period. These results further imply that early life consisted of an aminoacylated RNA world with a richer enzymatic potential than ribonucleotides alone

How Much Does Effortful Thinking Underlie Observers’ Reactions to Victimization?

From blaming to helping innocent victims, just-world research has revealed that observers react to victimization in a variety of ways. Recent research suggests that such responses to victimization require effortful thought, whereas other research has shown that people can react to these situations intuitively. Along with manipulating just-world threat, across seven experiments, we manipulated or measured participants’ level of mental processing before assessing judgments of victim derogation, blame, willingness to help, and ultimate justice reasoning. The effect of just-world threat on these responses held constant over a range of manipulations/measures, suggesting that the processes involved in maintaining a belief in a just world are not restricted to the rational, deliberative level of mental processing but also occur intuitively

Hypertonic saline reduces inflammation and enhances the resolution of oleic acid induced acute lung injury

<p>Abstract</p> <p>Background</p> <p>Hypertonic saline (HTS) reduces the severity of lung injury in ischemia-reperfusion, endotoxin-induced and ventilation-induced lung injury. However, the potential for HTS to modulate the resolution of lung injury is not known. We investigated the potential for hypertonic saline to modulate the evolution and resolution of oleic acid induced lung injury.</p> <p>Methods</p> <p>Adult male Sprague Dawley rats were used in all experiments. <b><it>Series 1 </it></b>examined the potential for HTS to reduce the severity of evolving oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 12) or hypertonic saline (HTS, n = 12), and the extent of lung injury assessed after 6 hours. <b><it>Series 2 </it></b>examined the potential for HTS to enhance the resolution of oleic acid (OA) induced acute lung injury. Following intravenous OA administration, animals were randomized to receive isotonic (Control, n = 6) or hypertonic saline (HTS, n = 6), and the extent of lung injury assessed after 6 hours.</p> <p>Results</p> <p>In <b><it>Series I</it></b>, HTS significantly reduced bronchoalveolar lavage (BAL) neutrophil count compared to Control [61.5 ± 9.08 versus 102.6 ± 11.89 × 10³ cells.ml^-1]. However, there were no between group differences with regard to: A-a O2 gradient [11.9 ± 0.5 vs. 12.0 ± 0.5 KPa]; arterial PO2; static lung compliance, or histologic injury. In contrast, in <b><it>Series 2</it></b>, hypertonic saline significantly reduced histologic injury and reduced BAL neutrophil count [24.5 ± 5.9 versus 46.8 ± 4.4 × 10³ cells.ml^-1], and interleukin-6 levels [681.9 ± 190.4 versus 1365.7 ± 246.8 pg.ml^-1].</p> <p>Conclusion</p> <p>These findings demonstrate, for the first time, the potential for HTS to reduce pulmonary inflammation and enhance the resolution of oleic acid induced lung injury.</p