3,673 research outputs found
Observability of hydrogen-rich exospheres in Earth-like exoplanets
(Abridged) The existence of an extended neutral hydrogen exosphere around
small planets can be used as an evidence for the presence of water in their
lower atmosphere but, to date, such feature has not been securely detected in
rocky exoplanets. Planetary exospheres can be observed using transit
spectroscopy of the Lyman- line, which is limited mainly by
interstellar medium absorption in the core of the line, and airglow
contamination from the geocorona when using low-orbit space telescopes. Our
objective is to assess the detectability of the neutral hydrogen exosphere of
an Earth-like planet transiting a nearby M dwarf using Lyman-
spectroscopy and provide the necessary strategies to inform future
observations. The spatial distribution in the upper atmosphere is provided by
an empirical model of the geocorona, and we assume a velocity distribution
based on radiative pressure as the main driver in shaping the exosphere. We
compute the excess absorption in the stellar Lyman- line while in
transit, and use realistic estimates of the uncertainties involved in
observations to determine the observability of the signal. We found that the
signal in Lyman- of the exosphere of an Earth-like exoplanet transiting
M dwarfs with radii between 0.1 and 0.6 R produces an excess absorption
between 50 and 600 ppm. The Lyman- flux of stars decays exponentially
with distance because of interstellar medium absorption, which is the main
observability limitation. Other limits are related to the stellar radial
velocity and instrumental setup. The excess absorption in Lyman- is
observable using LUVOIR/LUMOS in M dwarfs up to a distance of 15 pc. The
analysis of noise-injected data suggests that it would be possible to detect
the exosphere of an Earth-like planet transiting TRAPPIST-1 within 20 transits.Comment: 12 pages, 13 figures, accepted for publication in Astronomy &
Astrophysic
HSPB1 facilitates the formation of non-centrosomal microtubules
The remodeling capacity of microtubules (MT) is essential for their proper function. In mammals, MTs are predominantly formed at the centrosome, but can also originate from non-centrosomal sites, a process that is still poorly understood. We here show that the small heat shock protein HSPB1 plays a role in the control of non-centrosomal MT formation. The HSPB1 expression level regulates the balance between centrosomal and non-centrosomal MTs. The HSPB1 protein can be detected specifically at sites of de novo forming non-centrosomal MTs, while it is absent from the centrosomes. In addition, we show that HSPB1 binds preferentially to the lattice of newly formed MTs in vitro, suggesting that its function occurs by stabilizing MT seeds. Our findings open new avenues for the understanding of the role of HSPB1 in the development, maintenance and protection of cells with specialized non-centrosomal MT arrays
Lacking balancing market harmonisation in Europe: room for trader profits at the expense of economic efficiency?
Following several regional initiatives on the day-ahead and intra-day stage, integrating real-time balancing markets constitutes a logical next step in the process towards an Internal Electricity Market (IEM) in Europe. So far, realtime balancing market designs significantly differ between European countries and a coordinated approach for cross-border exchange of balancing services is non-existent. This paper aims to illustrate that the current lack of balancing market harmonisation – in combination with an increasingly integrated day-ahead and intra-day trade – can be profitably exploited by traders. More specifically, trading strategies taking advantage of structural design differences in the imbalance settlement of two countries are identified and assessed. The paper analyses detailed data of the Belgian and French power system using statistics in order to verify the profitability of different trading strategies between both countries. Some of the identified trading strategies are found to be significantly profitable; others turn out to be loss-making. On average, France was the most attractive country for traders to be long in 2008; Belgium to be short. Profitable trading strategies can usally be carried out without any expense as cross-border capacities available at the intra-day stage are currently far from being used and no value is attributed to them. However, some profitable trading activities resulting from market design imperfections may induce economic inefficiencies
Microtubule dynamics in the peripheral nervous system: A matter of balance
The special architecture of neurons in the peripheral nervous system, with axons extending for long distances, represents a major challenge for the intracellular transport system. Two recent studies show that mutations in the small heat shock protein HSPB1, which cause an axonal type of Charcot-Marie-Tooth (CMT) neuropathy, affect microtubule dynamics and impede axonal transport. Intriguingly, while at presymptomatic age the neurons in the mutant HSPB1 mouse show a hyperstable microtubule network, at postsymptomatic age, the microtubule network completely lost its stability as reflected by a marked decrease in tubulin acetylation levels. We here propose a model explaining the role of microtubule stabilization and tubulin acetylation in the pathogenesis of HSPB1 mutations
Experimental Test Plan DOE Tidal and River Reference Turbines
Our aim is to provide details of the experimental test plan for scaled model studies in St. Anthony Falls Laboratory (SAFL) Main Channel at the University of Minnesota, including a review of study objectives, descriptions of the turbine models, the experimental set-up, instrumentation details, instrument measurement uncertainty, anticipated experimental test cases, post-processing methods, and data archiving for model developers
Pembuatan Sistem Informasi Akuntansi Ekspedisi Muatan Kapal Laut 'X' Berbasis Web
EMKL ‘X’ adalah salah satu perusahaan ekspedisi muatan kapal laut yang
melayani pengiriman dan penerimaan kontener di Makassar. Perusahaan yang
memiliki tenaga kerja sebanyak 20 orang ini sedang menjalin kerja sama dengan
beberapa perusahaan ekspedisi di Jakarta dan Surabaya. Saat ini EMKL ‘X’ telah
menggunakan sistem berbasis
desktop
untuk pencatatan barang. Dengan
bergantinya sistem pencatatan manual tersebut menjadi sistem berbasis desktop,
permasalahan pencatatan kontener sudah dapat menjadi lebih efektif, tetapi timbul
masalah baru. Masalah tersebut adalah lamanya waktu pembuatan tagihan dan
kesibukan pemilik EMKL ‘X’ sehingga tida
k dapat selalu ada di tempat. Sistem
informasi akuntansi adalah suatu komponen organisasi yang mengumpulkan,
mengklarifikasikan, mengolah, menganalisis dan mengkomunikasikan informasi
finansial dan pengambilan keputusan yang relevan kepada pihak diluar dan
didalam perusahaan. Dengan adanya sistem informasi akuntansi berbasis web
untuk EMKL ‘X’ maka permasalahan dari EM
KL ‘X’ bisa teratasi. Hal ini sesuai
dengan tujuan dari pembuatan sistem informasi akuntansi in
Long-term survival in lung transplant recipients after successful preoperative coronary revascularization
ObjectiveCoronary artery disease is considered a contraindication to lung transplantation. We studied effect of pre-lung transplantation nonobstructive coronary artery disease and revascularized coronary artery disease on long-term lung transplant survival.MethodsClinical courses of 172 lung transplant recipients from December 1990 to May 2003 were reviewed. Significant coronary artery disease, defined as left main stenosis of greater than 50% or other epicardial vessel stenosis of greater than 70%, was present in 7 patients; 6 received percutaneous coronary intervention and 1 received coronary artery bypass grafting before transplantation.ResultsGroups were similar with regard to sex, race, or length of intensive care days. The group with normal coronary arteries was significantly younger than the groups with coronary artery disease. The revascularized group had a significant increase in dysrhythmias (P < .003) and 1-, 3-, and 5-year survivals of 85%, 85%, and 69%, respectively. Those with insignificant coronary artery disease (14 patients) demonstrated a 1-, 3-, and 5-year survival of 64%, 40%, and 32%, respectively. The normal coronary group (151 patients) had a 1-, 3-, and 5-year survival of 75%, 58%, and 40%, respectively. The revascularized group had a significant survival advantage compared with that of the insignificant coronary artery disease group (P < .04, log-rank test).ConclusionLong-term survival of lung transplant recipients with revascularized coronary arteries is similar to that of subjects with normal coronary arteries, despite an increased incidence of dysrhythmias. Lung transplant recipients with insignificant coronary artery disease had a worse survival than the revascularized group. More studies are needed to ascertain the cause and determine the optimal management for lung transplant recipients with insignificant coronary artery disease
Drug Repurposing for Duchenne Muscular Dystrophy: The Monoamine Oxidase B Inhibitor Safinamide Ameliorates the Pathological Phenotype in mdx Mice and in Myogenic Cultures From DMD Patients
Oxidative stress and mitochondrial dysfunction play a crucial role in the pathophysiology of muscular dystrophies. We previously reported that the mitochondrial enzyme monoamine oxidase (MAO) is a relevant source of reactive oxygen species (ROS) not only in murine models of muscular dystrophy, in which it directly contributes to contractile impairment, but also in muscle cells from Collagen VI-deficient patients. Here we now assessed the efficacy of a novel MAO-B inhibitor, safinamide, using in vivo and in vitro models of Duchenne muscular dystrophy (DMD). Specifically, we found that administration of safinamide in 3-month old mdx mice reduced myofiber damage and oxidative stress, and improved muscle functionality. In vitro studies with myogenic cultures from mdx mice and DMD patients showed that even cultured dystrophic myoblasts were more susceptible to oxidative stress than matching cells from healthy donors. Indeed, upon exposure to the MAO substrate tyramine or to hydrogen peroxide, DMD muscle cells displayed a rise in ROS levels and a consequent mitochondrial depolarization. Remarkably, both phenotypes normalized when cultures were treated with safinamide. Given that safinamide is already in clinical use for neurological disorders, our findings could pave the way towards a promising translation into clinical trials for DMD patients as a classic case of drug repurposing
Bisphenol and phthalate exposure during pregnancy and the development of childhood lung function and asthma. The Generation R Study
Background: Fetal exposure to bisphenols and phthalates may lead to alterations in the respiratory and immune system development in children, and to adverse respiratory health. Aim: To study the associations of fetal bisphenols and phthalates exposure with lung function and asthma at age 13 years. Study design and methods: This study among 1020 children was embedded in a population-based prospective cohort study. We measured maternal urine bisphenol and phthalate concentrations in the first, second and third trimester of pregnancy, and lung function by spirometry and asthma by questionnaires at age 13 years. Multivariable linear and logistic regression models were applied. Results: Maternal urine bisphenol and phthalate concentrations averaged during pregnancy were not associated with childhood lung function or asthma. Associations of maternal urine bisphenol and phthalate concentrations in specific trimesters with respiratory outcomes showed that one interquartile range increase in the natural log-transformed maternal urine mono-isobutyl phthalate concentration in the second trimester was associated with a higher FEV1/FVC, but not with asthma, accounting for confounders and multiple-testing correction. Although there were associations of higher second trimester bisphenol S with a lower FVC and FEV1 in boys and girls, and of higher first trimester bisphenol S with a decreased risk of asthma in boys and an increased risk of asthma in girls, these results did not remain significant after correction for multiple testing. Results were not modified by maternal history of asthma or atopy. Conclusions: Maternal urine bisphenol and phthalate concentrations averaged or in specific trimesters during pregnancy were not strongly associated with childhood lung function and asthma at age 13 years. BPS, as a BPA substitute, tended to be associated with impaired lung function and altered risk of asthma, partly sex-dependent, but its strength was limited by a relatively low detection rate and should be queried in contemporary cohorts.</p
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