Thermal instability in X-ray photoionized media in Active Galactic Nuclei: Influence on the gas structure and spectral features

A photoionized gas in thermal equilibrium can display a thermal instability, with 3 or more solutions in the multi-branch region of the S-shape curve giving the temperature versus the radiation-to-gas-pressure ratio. Many studies have been devoted to this curve and to its dependence on different parameters, always in the optically thin case. The purpose of our study is the thermal instability in optically thick, stratified media, in total pressure equilibrium. We have developped a new algorithm to select the hot/cold stable solution, and thereof to compute a fully consistent photoionization model. We have implemented it in the TITAN code and computed a set of models encompassing the range of conditions valid for the Warm Absorber in Active Galactic Nuclei. We have demonstrated that the thermal instability problem is quite different in thin or thick media. In thick media the spectral distribution changes as the radiation progresses inside the ionized gas. This has observational implications in the emitted/absorbed spectra, ionization states, and variability. However impossible to know what solution the plasma will adopt when attaining the multi-solutions regime, we expect the emitted/absorbed spectrum to be intermediate between those resulting from pure cold and hot models. Large spectral fluctuations corresponding to the onset of a cold/hot solution could be observed in timescales of the order of the dynamical time. A strong turbulence implying supersonic velocities should permanently exist in the multi-branch region of thick, stratified, pressure equilibrium media.Comment: LaTeX file: 18 pages, including 14 figures. Accepted for publication in Astronomy & Astrophysic

Escape probability methods versus "exact" transfer for modelling the X-ray spectrum of Active Galactic Nuclei and X-ray binaries

In the era of XMM-Newton and Chandra missions, it is crucial to use codes able to compute correctly the line spectrum of X-ray irradiated thick media (Thomson thickness of the order of unity) to build models for the structure and the emission of the central regions of AGN or X-ray binaries. In all photoionized codes except in our code Titan, the line intensities are computed with the "escape probability approximation". In its last version, Titan solves the transfer of a thousand lines and of the continuum with the ``Accelerated Lambda Iteration" method, which is one of the most efficient and most secure for line transfer. We find that for conditions typical of the AGN or X-ray binary emission medium, all escape approximations commonly used lead to an overestimation of the soft X-ray lines which can reach one order of magnitude for intense lines.Comment: 19 pages, 14 figures, accepted in A&

Advances in Electronic-Nose Technologies Developed for Biomedical Applications

The research and development of new electronic-nose applications in the biomedical field has accelerated at a phenomenal rate over the past 25 years. Many innovative e-nose technologies have provided solutions and applications to a wide variety of complex biomedical and healthcare problems. The purposes of this review are to present a comprehensive analysis of past and recent biomedical research findings and developments of electronic-nose sensor technologies, and to identify current and future potential e-nose applications that will continue to advance the effectiveness and efficiency of biomedical treatments and healthcare services for many years. An abundance of electronic-nose applications has been developed for a variety of healthcare sectors including diagnostics, immunology, pathology, patient recovery, pharmacology, physical therapy, physiology, preventative medicine, remote healthcare, and wound and graft healing. Specific biomedical e-nose applications range from uses in biochemical testing, blood-compatibility evaluations, disease diagnoses, and drug delivery to monitoring of metabolic levels, organ dysfunctions, and patient conditions through telemedicine. This paper summarizes the major electronic-nose technologies developed for healthcare and biomedical applications since the late 1980s when electronic aroma detection technologies were first recognized to be potentially useful in providing effective solutions to problems in the healthcare industry

The disruption of proteostasis in neurodegenerative diseases

Cells count on surveillance systems to monitor and protect the cellular proteome which, besides being highly heterogeneous, is constantly being challenged by intrinsic and environmental factors. In this context, the proteostasis network (PN) is essential to achieve a stable and functional proteome. Disruption of the PN is associated with aging and can lead to and/or potentiate the occurrence of many neurodegenerative diseases (ND). This not only emphasizes the importance of the PN in health span and aging but also how its modulation can be a potential target for intervention and treatment of human diseases.info:eu-repo/semantics/publishedVersio

Comparative analysis of the noncollagenous NC1 domain of type IV collagen: identification of structural features important for assembly, function, and pathogenesis.

Type IV collagen alpha1-alpha6 chains have important roles in the assembly of basement membranes and are implicated in the pathogenesis of Goodpasture syndrome, an autoimmune disorder, and Alport syndrome, a hereditary renal disease. We report comparative sequence analyses and structural predictions of the noncollagenous C-terminal globular NC1 domain (28 sequences). The inferred tree verified that type IV collagen sequences fall into two groups, alpha1-like and alpha2-like, and suggested that vertebrate alpha3/alpha4 sequences evolved before alpha1/alpha2 and alpha5/alpha6. About one fifth of NC1 residues were identified to confer either the alpha1 or alpha2 group-specificity. These residues accumulate opposite charge in subdomain B of alpha1 (positive) and alpha2 (negative) sequences and may play a role in the stoichiometric chain selection upon type IV collagen assembly. Neural network secondary structure prediction on multiple aligned sequences revealed a subdomain core structure consisting of six hydrophobic beta-strands and one short alpha-helix with a significant hydrophobic moment. The existence of opposite charges in the alpha-helices may carry implications for intersubdomain interactions. The results provide a rationale for defining the epitope that binds Goodpasture autoantibodies and a framework for understanding how certain NC1 mutations may lead to Alport syndrome. A search algorithm, based entirely on amino acid properties, yielded a possible similarity of NC1 to tissue inhibitor of metalloproteinases (TIMP) and prompted an investigation of a possible functional relationship. The results indicate that NC1 preparations decrease the activity of matrix metalloproteinases 2 and 3 (MMP-2, MMP-3) toward a peptide substrate, though not to [14C]-gelatin. We suggest that an ancestral NC1 may have been incorporated into type IV collagen as an evolutionarily mobile domain carrying proteinase inhibitor function

Sham sleep feedback delivered via actigraphy biases daytime symptom reports in people with insomnia: Implications for insomnia disorder and wearable devices

This study investigated whether providing sham feedback about sleep to individuals with insomnia influenced daytime symptom reports, sleep‐related attentional bias and psychomotor vigilance. Sixty‐three participants meeting DSM‐5 criteria for insomnia disorder were recruited from the community. Following baseline assessments and actigraphy briefing, participants were randomised to receive next‐day sham feedback on sleep quality (“positive” vs. “negative” sleep efficiency condition). Feedback was delivered at habitual rise‐time using an integrated actigraphy‐diary watch to simulate wearable device behaviour. Participants completed symptom reports immediately before receiving feedback, and at 12:00 and 15:00 hr, using the experience sampling method. Following this they returned to the laboratory in the evening to complete symptom reports and computerised tests of sleep‐related attentional bias and basic psychomotor vigilance. Participants randomised to negative feedback (n = 32) evidenced impaired daytime function (decreased alert cognition [d = 0.79], increased sleepiness/fatigue [d = 0.55]) in the evening compared with those given positive feedback (n = 31). Within‐day trajectories revealed that the positive‐feedback group, relative to the negative‐feedback group, displayed a significantly greater increase in positive mood and alert cognition (from rise‐time to 12:00 hr), and significantly greater decrease in sleepiness/fatigue. There were no significant between‐group differences on measures of sleep‐related attentional bias [d = 0.20] or psychomotor vigilance [d = 0.12]. This controlled experiment shows that sham feedback about sleep biases appraisal of daytime symptoms, highlighting a pathway connecting sleep misperception with daytime features of insomnia. Findings have important implications for wearable devices that claim to measure “objective” sleep yet may provide inaccurate data relative to gold‐standard measurement