103 research outputs found
GJ 357 b: A Super-Earth Orbiting an Extremely Inactive Host Star
In this paper we present a deep X-ray observation of the nearby M dwarf GJ
357 and use it to put constraints on the atmospheric evolution of its planet,
GJ 357 b. We also analyse the systematic errors in the stellar parameters of GJ
357 in order to see how they affect the perceived planetary properties. We
estimate the age of GJ 357 b by comparing the observed X-ray luminosity of its
host star, derived from a recent {\em XMM-Newton} observation {(), with age relations for M dwarfs. We
find that GJ 357 presents one of the lowest X-ray activity levels ever measured
for an M dwarf, and we put a lower limit on its age of \,Gyr.} Using this
age limit, we perform a backwards reconstruction of the original primordial
atmospheric reservoir. Furthermore, by considering the systematic errors in the
stellar parameters, we find a range of possible planetary masses, radii, and
densities. From the backwards reconstruction of GJ 357 b's irradiation history
we find that the upper limit of its initial primordial atmospheric mass is
. An initial atmospheric reservoir significantly larger
than this may have survived through the X-ray and ultraviolet irradiation
history, hence being inconsistent with current observations that suggest a
telluric composition. In spite of the unlikelihood of a currently existing
primordial envelope, volcanism and outgassing may have contributed to a
secondary atmosphere. Under this assumption, we present three different
synthetic infrared spectra for GJ 357 b that one might expect, consisting of
, , and , and .Comment: Accepted for publication in A&
An immunofluorescence study of the sarcoglycan sub- complex in gingival epithelium both in normal and in pathological conditions
Sarcoglycans are transmembrane glycoproteins which provide the connection between cytoskeleton and extracellular matrix. Sarcoglycans have been found in many kind of tissues as epithelial tissues where they seem to be involved in cell-cell and cell-extracellular matrix adhesion by their cadherin-like domains; by that, it was supported that sarcoglycans could be also involved in pathological condition of epithelial tissue. Moreover, we have already tested sarcoglycans in altered gingival epithelia of patients treated with bisphosphonates where we have observed that the sarcoglycans staining pattern is influenced by inflammatory condition. For these reasons we have continued our immunofluorescence study on sarcoglycans in gingival epithelia of patients treated with bisphosphonates and also in gingival epithelia of patients affected by periodontitis and scleroderma, two different pathological conditions where it is possible to observe inflammation and alteration of the gingival epithelium. Results obtained from normal samples have shown the presence of a staining pattern for each sarcoglycan in gingival epithelium; pathological results, instead, have shown that the entire sarcoglycan sub-complex changes in staining pattern level depending on the inflammation and alteration degree of the gingival epithelia. All these finding suggest us that sarcoglycans could play a key role in maintenance of epithelia architecture by their machanosignaling function, providing cell-cell and cell-extracellular matrix adhesion using their cadherin like domain
Does \u2018bigger\u2019mean \u2018better\u2019? Pitfalls and shortcuts associated with big data for social research
\u2018Big data is here to stay.\u2019 This key statement has a double value: is an assumption as well as the reason why a theoretical reflection is needed. Furthermore, Big data is something that is gaining visibility and success in social sciences even, overcoming the division between humanities and computer sciences. In this contribution some considerations on the presence and the certain persistence of Big data as a socio-technical assemblage will be outlined. Therefore, the intriguing opportunities for social research linked to such interaction between practices and technological development will be developed. However, despite a promissory rhetoric, fostered by several scholars since the birth of Big data as a labelled concept, some risks are just around the corner. The claims for the methodological power of bigger and bigger datasets, as well as increasing speed in analysis and data collection, are creating a real hype in social research. Peculiar attention is needed in order to avoid some pitfalls. These risks will be analysed for what concerns the validity of the research results \u2018obtained through Big data. After a pars distruens, this contribution will conclude with a pars construens; assuming the previous critiques, a mixed methods research design approach will be described as a general proposal with the objective of stimulating a debate on the integration of Big data in complex research projecting
The connection between basal ganglia and cerebellum in human brain
Our recent anatomical studies on direct connections between the cerebral cortex and medial pallidum nucleus, we observed the presence of interesting connections between this nucleus and the cerebellum, highlighting as these subcortical structures are part of a densely interconnected network. Through DTI method with Constrained Deconvolution System (CDS) techniques we evaluated these connections in ten healthy subjects and in three patients with Parkinson’s syndrome. Our results demonstrate that the pathways linking the cerebellum to basal ganglia are topographically organized. Furthermore, the cerebellum not only provides output exclusively to the primary motor cortex via the thalamus for the motor control and coordination of movements but it is involved in the process of lock and un-lock of the motor gesture through the planning role of the basal ganglia. These pathways provide evidence for substantial communication between the cerebellum and the basal ganglia that is independent of the cerebral cortex. Communication between these major subcortical nuclei is likely to have important clinical implications. We discuss how the pathways linking the cerebellum with the basal ganglia may provide a useful framework for understanding cerebellar contributions to the manifestation of two prototypical basal ganglia disorders, Parkinson’s disease and dystonia
Whole-brain histogram and voxel-based analyses of apparent diffusion coefficient and magnetization transfer ratio in celiac disease, epilepsy, and cerebral calcifications syndrome
BACKGROUND AND PURPOSE: Diffusion and magnetization transfer (MT) techniques have been applied to the investigation with MR of epilepsy and have revealed changes in patients with or without abnormalities on MR imaging. We hypothesized that also in the coeliac disease (CD), epilepsy and cerebral calcifications (CEC) syndrome diffusion and MT techniques could reveal brain abnormalities undetected by MR imaging and tentatively correlated to epilepsy.
MATERIALS AND METHODS: Diffusion and MT weighted images were obtained in 10 patients with CEC, 8 patients with CD without epilepsy and 17 healthy volunteers. The whole brain apparent diffusion coefficient (ADC) and MT ratio (MTR) maps were analyzed with histograms and the Statistical Parametric Mapping 2 (SPM2) software. We employed the non-parametric Mann-Whitney U test to assess differences for ADC and MTR histogram metrics. Voxel by voxel comparison of the ADC and MTR maps was performed with 2 tails t-test corrected for multiple comparison.
RESULTS: A significantly higher whole brain ADC value as compared to healthy controls was observed in CEC (P = 0.006) and CD (P = 0.01) patients. SPM2 showed bilateral areas of significantly decreased MTR in the parietal and temporal subcortical white matter (WM) in the CEC patients.
CONCLUSION: Our study indicates that diffusion and MT techniques are also capable of revealing abnormalities undetected by MR imaging. In particular patients with CEC syndrome show an increase of the whole brain ADC histogram which is more pronounced than in patients with gluten intolerance. IN CEC patients, voxel-based analysis demonstrates a localized decrease of the MTR in the parieto-temporal subcortical WM
A 3d and 4d anatomical study of the human heart: analysis by direct volume rendering technique
In this report we demonstrated an innovative use of 3D and 4D volume rendering, processing the data set images obtained by CT on heart of subjects not affected by any cardiologic disorders. This method is a direct technique for visualizing primitive volumes without any intermediate conversion of the volume data to surface presentation. Here, we are able to highlight all anatomical structures of the heart examining them contemporarily in the same image or selecting a tissue type. The present report demonstrates how the manipulation of appropriate algorithms permits to meliorate the interactive anatomical morphology visualization, observing the heart within thorax, contemporarily, and creating a good perception of depth. Besides, it was possible to study the integrity of papillary muscles, or the fibrous tissue of cardiac valve and cordae tendineae, or finally to designate the exact morphology and location of coronary arteries studying and describing their wall morphology. Furthermore, by 4D analysis it was possible to obtain three-dimensional images in movement, highlighting both the movement of the vessels during cardiac phases and the modification of internal cardiac structures during these phases. Our results demonstrated that one of the greatest advantage of algorithmic modifications of volume rendering is that this method provides all the necessary informations in a single radiologic study, meliorating anatomical description of all cardiac structures. Moreover, avoiding the invasive diagnostic methods as well as coronarography this methods allows to meliorate clinical study of the region also facilitating the therapeutic plans of the cardiac disease
Practice ecology of sustainable travel: The importance of institutional policy-making processes beyond the traveller
© 2019 The Authors Changing mobility behaviour towards activities and actions that have a less detrimental impact on the environment, public health and society is an objective of transport policy jurisdictions globally. In line with a burgeoning body of research examining behaviour and social change, this paper explores the governmental systems that influence mobility behaviours through a social practice lens. This paper blends two social practice theoretical models, the ‘3-Elements Model’ and ‘Systems of Provision’ as a means of understanding the delivery of the Local Sustainable Transport Fund (LSTF), a central government grant scheme for English local authorities. We examine how the meanings, materials and competences within the practices of bid writing by local authorities and scheme selection by government influenced the distribution of funding to local authorities. The research starts from the principle that, where funding is provided by central government, in the case of this research that of the UK, an opportunity is created for mobility practices to change. The significance of funding is not easily theorised by the 3-Elements model but is more helpfully explained when that model is blended with the wider Systems of Provision model to create a model of practice ecology. Our theorisation allows for a rigorous exploration of the ‘practice scaffolding’ which shapes how people travel. Policymakers are recommended to consider a practice ecology approach when developing mobility management schemes to tackle air quality, climate change and obesity issues more effectively
Bottom-up Infrastructures: Aligning Politics and Technology in building a Wireless Community Network
Contemporary innovation in infrastructures is increasingly characterized by a close relationship between experts and lay people. This phenomenon has attracted the attention from a wide range of disciplines, including computer-supported cooperative work (CSCW), science and technology studies (S&TS), organization studies and participatory design (PD). Connecting to this broad area of research, the article presents a qualitative case study concerning the building and maintenance of a grassroots, bottom-up information infrastructure in Italy, defined as wireless community network (WCN). Methodologically, the research is based on qualitative interviews with participants to the WCN, ethnographic observations and document analysis. The aim of the article is to understand the alignment between the technical work implied in building this bottom-up infrastructure and the political and cultural frameworks that move people to participate to this project. Relying on the field of science & technology studies, and in particular on the notions of ‘inverse infrastructure’ and ‘research in the wild’, we disclose the WCN’s peculiar innovation trajectory, localized outside conventional spaces of research and development. Overall, the presentation of the qualitative and ethnographic data allows to point out a more general reflection on bottom-up infrastructures and to enrich the academic debate concerning bottom-up infrastructuring work and other similar typologies of collaborative design projects in the domain of infrastructures
Recommended from our members
Interstitial Spaces: Microinteraction Settings and the Genesis of New Practices Between Institutional Fields
I develop a model linking specific microinteraction dynamics between members of different institutional fields and the genesis of new practices. The model centers on the concept of interstitial spaces—that is, small-scale settings where individuals from different fields interact occasionally and informally around common activities to which they devote limited time (e.g., hobbyist clubs, hangouts, workshops, meet-ups). I argue that the features of interstitial spaces (e.g., their institutional diversity and their occasional and informal nature) facilitate the individuals interacting in these settings to temporarily break free from existing institutions and experiment collectively with new activities and ideas. However, these very same features hinder the constitution of such new activities and ideas into new practices. I identify two microlevel conditions that enable the new activities and ideas developed in interstitial spaces to be constituted into new practices: the emergence of successful interaction rituals, and the presence of catalysts sustaining others' interactions and assisting the construction of shared meanings
- …