Accretion and ejection in black-hole X-ray transients

Aims: We summarize the current observational picture of the outbursts of black-hole X-ray transients (BHTs), based on the evolution traced in a hardness-luminosity diagram (HLD), and we offer a physical interpretation. Methods: The basic ingredient in our interpretation is the Poynting-Robertson Cosmic Battery (PRCB, Contopoulos & Kazanas 1998), which provides locally the poloidal magnetic field needed for the ejection of the jet. In addition, we make two assumptions, easily justifiable. The first is that the mass-accretion rate to the black hole in a BHT outburst has a generic bell-shaped form. This is guaranteed by the observational fact that all BHTs start their outburst and end it at the quiescent state. The second assumption is that at low accretion rates the accretion flow is geometrically thick, ADAF-like, while at high accretion rates it is geometrically thin. Results: Both, at the beginning and the end of an outburst, the PRCB establishes a strong poloidal magnetic field in the ADAF-like part of the accretion flow, and this explains naturally why a jet is always present in the right part of the HLD. In the left part of the HLD, the accretion flow is in the form of a thin disk, and such a disk cannot sustain a strong poloidal magnetic filed. Thus, no jet is expected in this part of the HLD. The counterclockwise traversal of the HLD is explained as follows: the poloidal magnetic field in the ADAF forces the flow to remain ADAF and the source to move upwards in the HLD rather than to turn left. Thus, the history of the system determines the counterclockwise traversal of the HLD. As a result, no BHT is expected to ever traverse the entire HLD curve in the clockwise direction. Conclusions: We offer a physical interpretation of accretion and ejection in BHTs with only one parameter, the mass transfer rate.Comment: Accepted for publication in A&

An overview of jets and outflows in stellar mass black holes

In this book chapter, we will briefly review the current empirical understanding of the relation between accretion state and and outflows in accreting stellar mass black holes. The focus will be on the empirical connections between X-ray states and relativistic (`radio') jets, although we are now also able to draw accretion disc winds into the picture in a systematic way. We will furthermore consider the latest attempts to measure/order jet power, and to compare it to other (potentially) measurable quantities, most importantly black hole spin.Comment: Accepted for publication in Space Science Reviews. Also to appear in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher

Genetic research: the role of citizens, public health and international stakeholders

Background: Genetic research has become an indispensable instrument for medical research, and the subjects involved have both divergent and convergent interests. Objective: The possibility of having more detailed genetic information undoubtedly offers benefits for the health of the subject, but could also pose risks and make the subject vulnerable to discrimination. Methods: The scientific community has viewed very favorably the public health utility of family history, in which data from a family whose members suffer from chronic pathologies is collected and filed, in order to develop a sort of “stratification of family risk.” Even though in the last decade the scientific and juridical literature has contributed greatly to the topic of biobanks, the perplexities that continue to surround this theme give the idea that current ethical protocols on research are inadequate. Results: Researchers, citizens, International stakeholders, mass media, Public Health and Governments play a key role in genetic research. It is obvious that the methods used for genetic research do not present intrinsic risks; they are much less dangerous than other activities of diagnosis and research. Before authorizing a research project, it is important to reflect on the responsibility and transparency of the studies to be conducted, and on the impact they may have on the interests of public health. Conclusion: We believe that the highest priority need is to develop a common language on the theme, as is the case in the sphere of clinical experimentation where rules of good clinical practice, albeit at times conflicting, have led to uniform convergences in the scientific world on the points to be actuated

Primordial Nucleosynthesis for the New Cosmology: Determining Uncertainties and Examining Concordance

Big bang nucleosynthesis (BBN) and the cosmic microwave background (CMB) have a long history together in the standard cosmology. The general concordance between the predicted and observed light element abundances provides a direct probe of the universal baryon density. Recent CMB anisotropy measurements, particularly the observations performed by the WMAP satellite, examine this concordance by independently measuring the cosmic baryon density. Key to this test of concordance is a quantitative understanding of the uncertainties in the BBN light element abundance predictions. These uncertainties are dominated by systematic errors in nuclear cross sections. We critically analyze the cross section data, producing representations that describe this data and its uncertainties, taking into account the correlations among data, and explicitly treating the systematic errors between data sets. Using these updated nuclear inputs, we compute the new BBN abundance predictions, and quantitatively examine their concordance with observations. Depending on what deuterium observations are adopted, one gets the following constraints on the baryon density: OmegaBh^2=0.0229\pm0.0013 or OmegaBh^2 = 0.0216^{+0.0020}_{-0.0021} at 68% confidence, fixing N_{\nu,eff}=3.0. Concerns over systematics in helium and lithium observations limit the confidence constraints based on this data provide. With new nuclear cross section data, light element abundance observations and the ever increasing resolution of the CMB anisotropy, tighter constraints can be placed on nuclear and particle astrophysics. ABRIDGEDComment: 54 pages, 20 figures, 5 tables v2: reflects PRD version minor changes to text and reference

Effects of a mosquitocidal toxin on a mammalian epithelial cell line expressing its target receptor.

The spread of diseases transmitted by Anopheles and Culex mosquitoes, such as malaria and West Nile fever, is a growing concern for human health. Bacillus sphaericus binary toxin (Bin) is one of the few available bioinsecticides able to control populations of these mosquitoes efficiently. We previously showed that Bin binds to Cpm1, an alpha-glucosidase located on the apical side of Culex larval midgut epithelium. We analysed the effects of Bin by expressing a construct encoding Cpm1 in the mammalian epithelial MDCK cell line. Cpm1 is targeted to the apical side of polarized MDCK, where it is anchored by glycosylphosphatidylinositol (GPI) and displays alpha-glucosidase activity. Bin bound to transfected cells and induced a non-specific current presumably related to the opening of pores. The formation of these pores may be related to the location of the toxin/receptor complex in lipid raft microdomains. Finally, Bin promoted the time-dependent appearance of intracytoplasmic vacuoles but did not drive cell lysis. Thus, the dual functionality (enzyme/toxin receptor) of Cpm1 is fully conserved in MDCK cells and Cpm1 is an essential target protein for Bin cytotoxicity in Culex mosquitoes

Codon-optimized glucoamylase sGAI of Aspergillus awamori improves starch utilization in an industrial yeast

ArticleThe development of a yeast that converts raw starch to ethanol in one step (called consolidated bioprocessing) could yield large cost reductions in the bioethanol industry. The aim of this study was to develop an efficient amylolytic Saccharomyces cerevisiae strain suitable for industrial bioethanol production. A native and codon-optimized variant of the Aspergillus awamori glucoamylase gene were expressed in the S. cerevisiae Y294 laboratory strain. Codon optimization resulted to be effective and the synthetic sequence sGAI was then d-integrated into a S. cerevisiae strain with promising industrial fermentative traits. The mitotically stable recombinant strains showed high enzymatic capabilities both on soluble and raw starch (2425 and 1140 nkat/g dry cell weight, respectively). On raw corn starch, the engineered yeasts exhibited improved fermentative performance with an ethanol yield of 0.42 (g/g), corresponding to 75 % of the theoretical maximum yield. © Springer-Verlag 2012

Antiangiogenics in Choroidal Neovascularization associated with laser in central serous Chorioretinopathy

Background/Purpose: To report characteristics and treatment outcome of choroidal neovascularization (CNV) secondary to laser photocoagulation and photodynamic therapy (PDT) in central serous chorioretinopathy. Methods: Retrospective analysis of 12 eyes of 12 patients, who were diagnosed to have CNV secondary to laser photocoagulation or PDT for central serous chorioretinopathy. Collected data included demographic details, history of presenting illness, clinical examination details including visual acuity at presentation, and follow-up with imaging and treatment details. Main outcome measures were resolution of CNV activity at the last follow-up. Secondary outcomes included change in visual acuity at final follow-up from baseline, number of injections, treatment-free interval, and adverse events. Results: This study included 12 eyes of CNV secondary to laser photocoagulation (8 eyes) and PDT (4 eyes). Mean age of study subjects was 47.6 \ub1 15.4 years (range 33-82) with 8 men and 4 women. Mean interval between laser photocoagulation/PDT and diagnosis of CNV was 23.9 \ub1 54.5 months. All subjects had unilateral CNV with classic CNV on fluorescein angiography. Eight eyes had extrafoveal CNV, and four eyes had juxtafoveal CNV. Baseline best-corrected visual acuity was 0.56 \ub1 0.51 (Snellen equivalent 20/60) logMAR, and final best-corrected visual acuity was 0.53 \ub1 0.51 (Snellen equivalent 20/60) logMAR with no significant difference (P 0.84). All four eyes that presented with the CNV secondary to PDT group required additional PDT treatment because of poor response to antivascular endothelial growth factor therapy. At the last follow-up, only one patient in the laser group had active CNV; the remaining patients of both groups had scarred CNV. Mean follow-up duration was 22.4 \ub1 23.1 months. Mean number of injections was 3.16 \ub1 2.62. Longest treatment-free interval was 8.29 \ub1 11.4 months. Conclusion: Antivascular endothelial growth factor therapy appears to be safe and efficacious in CNVs secondary to laser photocoagulation and PDT. Choroidal neovascularizations secondary to PDT appear to be more resistant to antivascular endothelial growth factor therapy than those because of laser photocoagulation and required additional PDT

Outcomes of treatment of choroidal neovascularization associated with central serous chorioretinopathy with intravitreal antiangiogenic agents

Purpose: To report clinical characteristics and treatment outcomes from the largest case series of choroidal neovascularization secondary to central serous chorioretinopathy. Methods: Retrospective analysis of 46 eyes of 43 consecutive subjects. Collected data included demographic details, history of presenting illness, clinical examination details including visual acuity at presentation and follow-up with imaging and treatment details. Main outcome measures were the proportion of eyes that had improved (3 or more lines), stable (within \ub11 line), or decreased (3 or more lines) vision at the final visit as compared with baseline examination. Secondary efficacy outcomes included change in visual acuity at final follow-up, number of injections, treatment-free interval, and adverse events. Results: Mean age was 57.56 years (range 29-79 years). Mean follow-up duration was 38.3 months \ub1 58.9 months. More than 3 lines of improvement in 12 eyes (26%), vision was stable (within \ub11 line) in 19 eyes (41.3%), and .3 lines of loss was noted in 6 eyes (13%). Mean change in the number of lines was 1.16 \ub1 3.74. Mean number of anti-vascular endothelial growth factor injections during the follow-up was 4.45 \ub1 4.1. The longest treatment-free interval was 8.9 months \ub1 7.5 months. There were no adverse events noted. Conclusion: Anti-vascular endothelial growth factor therapy as a primary therapy for choroidal neovascularization secondary to central serous chorioretinopathy is safe and efficacious, without any serious adverse events