TRACE and ground-based observations of microflares

We present high temporal and spatial resolution, multiwavelength observations of small-scale activity phenomena. The data were obtained during a coordinated campaign between ground-based and space observatories. Our analysis supports the concept that small flares are just miniature flares, i.e. that the same physical processes are at work, but that it is mandatory to have an excellent resolution in order to clearly identify them. In particular, we find that chromospheric downward motions are a very distinctive characteristic of the flare phenomenon even in tiny events

Flare model sensitivity of the Balmer spectrum

Careful studies of various chromospheric spectral signatures are very important in order to explore their possible sensitivity to the modifications of the thermodynamic quantities produced by the flare occurrence. Pioneer work of Canfield and co-workers have shown how the H alpha behavior is able to indicate different changes in the atmospheric parameters structure associated to the flare event. It was decided to study the behavior of the highest Balmer lines and of the Balmer continuum in different solar flare model atmospheres. These spectral features, originating in the deep photosphere in a quiet area, may have a sensitivity different from H alpha to the modification of a flare atmosphere. The details of the method used to compute the Stark profile of the higher Balmer line (n is greater than or equal to 6) and their merging were extensively given elsewhere (Donati-Falchi et al., 1985; Falchi et al., 1989). The models used were developed by Ricchiazzi in his thesis (1982) evaluating the chromospheric response to both the nonthermal electron flux, for energy greater than 20 kev, (F sub 20) and to the thermal conduction, (F sub c). The effect of the coronal pressure values (P sub O) at the apex of the flare loop is also included

Helium Line Formation and Abundance in a Solar Active Region

An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca ii K, H , and Na i D, as well as He i 10830, 5876, 584, and He ii 304 8 lines have been observed. The EUV radiation in the range k < 500 8 and in the range 260 < k < 340 8 has also been measured at the same time. These simultaneous observations allow us to build semiempirical models of the chromosphere and low transition region of an active region, taking into account the estimated total number of photoionizing photons impinging on the target active region and their spectral distribution. We obtained a model that matches very well all the observed line profiles, using a standard value for the He abundance (½He ¼ 0:1) and a modified distribution of microturbulence. For this model we study the influence of the coronal radiation on the computed helium lines. We find that, even in an active region, the incident coronal radiation has a limited effect on the UV He lines, while it is of fundamental importance for the D3 and 10830 8 lines. Finally, we build two more models, assuming values of He abundance ½He ¼ 0:07 and 1.5, only in the region where temperatures are >1 ; 104 K. This region, between the chromosphere and transition region, has been indicated as a good candidate for processes that might be responsible for strong variations of [He]. The set of our observables can still be well reproduced in both cases, changing the atmospheric structure mainly in the low transition region. This implies that, to choose between different values of [He], it is necessary to constrain the transition region with different observables, independent of the He lines.Fil: Mauas, Pablo Jacobo David. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Andretta, V.. Osservatorio Astronomico di Capodimonte; ItaliaFil: Falchi, A.. Osservatorio Astrofisico di Arcetri; ItaliaFil: Falciani, R.. Universita Degli Studi Di Firenze; ItaliaFil: Teriaca, L.. Max-Planck-Institut fur Sonnensystemforschung; AlemaniaFil: Cauzzi, G.. Osservatorio Astrofisico di Arcetri; Itali

A Systems Biology Approach Reveals a Calcium-Dependent Mechanism for Basal Toxicity in Daphnia magna.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Environmental Science & Technology, copyright © American Chemical Society after peer review and technical editing by the publisher.The expanding diversity and ever increasing amounts of man-made chemicals discharged to the environment pose largely unknown hazards to ecosystem and human health. The concept of adverse outcome pathways (AOPs) emerged as a comprehensive framework for risk assessment. However, the limited mechanistic information available for most chemicals and a lack of biological pathway annotation in many species represent significant challenges to effective implementation of this approach. Here, a systems level, multistep modeling strategy demonstrates how to integrate information on chemical structure with mechanistic insight from genomic studies, and phenotypic effects to define a putative adverse outcome pathway. Results indicated that transcriptional changes indicative of intracellular calcium mobilization were significantly overrepresented in Daphnia magna (DM) exposed to sublethal doses of presumed narcotic chemicals with log Kow ≥ 1.8. Treatment of DM with a calcium ATPase pump inhibitor substantially recapitulated the common transcriptional changes. We hypothesize that calcium mobilization is a potential key molecular initiating event in DM basal (narcosis) toxicity. Heart beat rate analysis and metabolome analysis indicated sublethal effects consistent with perturbations of calcium preceding overt acute toxicity. Together, the results indicate that altered calcium homeostasis may be a key early event in basal toxicity or narcosis induced by lipophilic compounds

Echocardiography and pulse contour analysis to assess cardiac output in trauma patients.

Echocardiography is a valuable technique to assess cardiac output (CO) in trauma patients, but it does not allow a continuous bedside monitoring. Beat-to-beat CO assessment can be obtained by other techniques, including the pulse contour method MostCare. The aim of our study was to compare CO obtained with MostCare (MC-CO) with CO estimated by transthoracic echocardiography (TTE-CO) in trauma patients. METHODS: Forty-nine patients with blunt trauma admitted to an intensive care unit and requiring hemodynamic optimization within 24 hours from admission were studied. TTE-CO and MC-CO were estimated simultaneously at baseline, after a fluid challenge and after the start of vasoactive drug therapy. RESULTS: One hundred sixteen paired CO values were obtained. TTE-CO values ranged from 2.9 to 7.6 L·min-1, and MC-CO ranged from 2.8 to 8.2 L·min-1. The correlation between the two methods was 0.94 (95% confidence interval [CI] = 0.89 to 0.97; p<0.001). The mean bias was -0.06 L·min-1 with limits of agreements (LoA) of -0.94 to 0.82 L·min-1 (lower 95% CI, -1.16 to -0.72; upper 95% CI, 0.60 to 1.04) and a percentage error of 18%. Changes in CO showed a correlation of 0.91 (95% CI = 0.87 to 0.95; p<0.001), a mean bias of - 0.01 L·min-1 with LoA of -0.67 to 0.65 L·min-1 (lower 95% CI, -0.83 to -0.51; upper 95% CI, 0.48 to 0.81). CONCLUSION: CO measured by MostCare showed good agreement with CO obtained by transthoracic echocardiography. Pulse contour analysis can complement echocardiography in evaluating hemodynamics in trauma patients

MMP13 and TIMP1 are functional markers for two different potential modes of action by mesenchymal stem/stromal cells when treating osteoarthritis

Mesenchymal stem cells (MSCs) have been investigated as a potential injectable therapy for the treatment of knee osteoarthritis, with some evidence of success in preliminary human trials. However, optimization and scale‐up of this therapeutic approach depends on the identification of functional markers that are linked to their mechanism of action. One possible mechanism is through their chondrogenic differentiation and direct role in neo‐cartilage synthesis. Alternatively, they could remain undifferentiated and act through the release of trophic factors that stimulate endogenous repair processes within the joint. Here, we show that extensive in vitro aging of bone marrow‐derived human MSCs leads to loss of chondrogenesis but no reduction in trophic repair, thereby separating out the two modes of action. By integrating transcriptomic and proteomic data using Ingenuity Pathway Analysis, we found that reduced chondrogenesis with passage is linked to downregulation of the FOXM1 signaling pathway while maintenance of trophic repair is linked to CXCL12. In an attempt at developing functional markers of MSC potency, we identified loss of mRNA expression for MMP13 as correlating with loss of chondrogenic potential of MSCs and continued secretion of high levels of TIMP1 protein as correlating with the maintenance of trophic repair capacity. Since an allogeneic injectable osteoar therapy would require extensive cell expansion in vitro, we conclude that early passage MMP13+, TIMP1‐secretinghigh MSCs should be used for autologous OA therapies designed to act through engraftment and chondrogenesis, while later passage MMP13−, TIMP1‐secretinghigh MSCs could be exploited for allogeneic OA therapies designed to act through trophic repair