Context. The transport of angular momentum is fundamental during the formation of low-mass stars; too little removal and rotation ensures stellar densities are never reached, too much and the absence ...of rotation means no protoplanetary disks can form. Magnetic diffusion is seen as a pathway to resolving this long-standing problem. Aims. We aim to investigate the impact of including resistive magnetohydrodynamics (MHD) in simulations of the gravitational collapse of a 1 M⊙ gas sphere, from molecular cloud densities to the formation of the protostellar seed; the second Larson core. Methods. We used the adaptive mesh refinement code RAMSES to perform two 3D simulations of collapsing magnetised gas spheres, including self-gravity, radiative transfer in the form of flux-limited diffusion, and a non-ideal gas equation of state to describe H2 dissociation which leads to the second collapse. The first run was carried out under the ideal MHD approximation, while ambipolar and ohmic diffusion was incorporated in the second calculation using resistivities computed from an equilibrium chemical network. Results. In the ideal MHD simulation, the magnetic field dominates the energy budget everywhere inside and around the first hydrostatic core, fueling interchange instabilities and driving a low-velocity outflow above and below the equatorial plane of the system. High magnetic braking removes essentially all angular momentum from the second core. On the other hand, ambipolar and ohmic diffusion create a barrier which prevents amplification of the magnetic field beyond 0.1 G in the first Larson core which is now fully thermally supported. A significant amount of rotation is preserved and a small Keplerian-like disk forms around the second core. The ambipolar and ohmic diffusions are effective at radii below 10 AU, indicating that a least ~1 AU is necessary to investigate the angular momentum transfer and the formation of rotationally supported disks. Finally, when studying the radiative efficiency of the first and second core accretion shocks, we found that it can vary by several orders of magnitude over the 3D surface of the cores. Conclusions. This proves that magnetic diffusion is a prerequisite to star formation. Not only does it enable the formation of protoplanetary disks in which planets will eventually form, it also plays a determinant role in the formation of the protostar itself.
Today, regenerative osteogenesis represents a clinical need, due to the incidence of bone defects that involve groups of pathologies ranging from congenital anomalies to traumatic injuries, as well ...as problems presented surgically. This is why the design of a polymeric biomaterial (scaffold) of chitosan, carboxymethylcellulose, zinc oxide, and calcium carbonate with similar characteristics in terms of composition and bone structure offers high potential to help address this health problem. The technique for obtaining the scaffolds of this research was to develop a physical hydrogel to have the biofunctionality of the active groups of the polymer chains used, then make use of the lyophilization process to obtain three-dimensional (3D) porous scaffolds. The physicochemical and biological properties of the scaffolds were evaluated. The scaffolds presented morphology with pore size and interconnectivity that favor the need for cell proliferation and viability. The biocompatibility tests confirm that the designed scaffolds do not present cytotoxicity and the analyzes with alizarin red staining show calcium deposits in the materials with CaCO3 and ZnO. Osteoinduction assays to osteogenic lineage using runt-related transcription factor type 2 (RUNX2) and collagen type 1 (COL-1) antibodies allowed expression in differentiated cells. Therefore, the calcium carbonate-containing scaffolds stabilized by physical bonds have characteristics of being non-cytotoxic, bioactive, and osteoinductive, which motivate their use in future tests to evaluate their demeanor with rat models for bone engineering studies.
Graphical Abstract
We present the first catalog of TeV gamma-ray sources realized with data from the newly completed High Altitude Water Cherenkov Observatory (HAWC). It is the most sensitive wide field-of-view TeV ...telescope currently in operation, with a one-year survey sensitivity of ∼5%-10% of the flux of the Crab Nebula. With an instantaneous field of view >1.5 sr and >90% duty cycle, it continuously surveys and monitors the sky for gamma-ray energies between hundreds of GeV and tens of TeV. HAWC is located in Mexico, at a latitude of 19° N, and was completed in 2015 March. Here, we present the 2HWC catalog, which is the result of the first source search performed with the complete HAWC detector. Realized with 507 days of data, it represents the most sensitive TeV survey to date for such a large fraction of the sky. A total of 39 sources were detected, with an expected number of false detections of 0.5 due to background fluctuation. Out of these sources, 19 are new sources that are not associated with previously known TeV sources (association criteria: <0 5 away). The source list, including the position measurement, spectrum measurement, and uncertainties, is reported, then each source is briefly discussed. Of the 2HWC associated sources, 10 are reported in TeVCat as PWN or SNR: 2 as blazars and the remaining eight as unidentified.
Abstract
Mobile medical imaging devices are invaluable for clinical diagnostic purposes both in and outside healthcare institutions. Among the various imaging modalities, only a few are readily ...portable. Magnetic resonance imaging (MRI), the gold standard for numerous healthcare conditions, does not traditionally belong to this group. Recently, low-field MRI technology companies have demonstrated the first decisive steps towards portability within medical facilities and vehicles. However, these scanners’ weight and dimensions are incompatible with more demanding use cases such as in remote and developing regions, sports facilities and events, medical and military camps, or home healthcare. Here we present in vivo images taken with a light, small footprint, low-field extremity MRI scanner outside the controlled environment provided by medical facilities. To demonstrate the true portability of the system and benchmark its performance in various relevant scenarios, we have acquired images of a volunteer’s knee in: (i) an MRI physics laboratory; (ii) an office room; (iii) outside a campus building, connected to a nearby power outlet; (iv) in open air, powered from a small fuel-based generator; and (v) at the volunteer’s home. All images have been acquired within clinically viable times, and signal-to-noise ratios and tissue contrast suffice for 2D and 3D reconstructions with diagnostic value. Furthermore, the volunteer carries a fixation metallic implant screwed to the femur, which leads to strong artifacts in standard clinical systems but appears sharp in our low-field acquisitions. Altogether, this work opens a path towards highly accessible MRI under circumstances previously unrealistic.
Toll-like receptors (TLRs) have garnered an extraordinary amount of interest in cancer research due to their role in tumor progression. By activating the production of several biological factors, ...TLRs induce type I interferons and other cytokines, which drive an inflammatory response and activate the adaptive immune system. The aim of this study was to investigate the expression and clinical relevance of TLR3, 4 and 9 in breast cancer.
The expression levels of TLR3, TLR4 and TLR9 were analyzed on tumors from 74 patients with breast cancer. The analysis was performed by immunohistochemistry.
Samples of carcinomas with recurrence exhibited a significant increase in the mRNA levels of TLR3, TLR4 and TLR9. Tumors showed high expression of TLRs expression levels by cancer cells, especially TLR4 and 9. Nevertheless, a significant percentage of tumors also showed TLR4 expression by mononuclear inflammatory cells (21.6%) and TLR9 expression by fibroblast-like cells (57.5%). Tumors with high TLR3 expression by tumor cell or with high TLR4 expression by mononuclear inflammatory cells were significantly associated with higher probability of metastasis. However, tumours with high TLR9 expression by fibroblast-like cells were associated with low probability of metastasis.
The expression levels of TLR3, TLR4 and TLR9 have clinical interest as indicators of tumor aggressiveness in breast cancer. TLRs may represent therapeutic targets in breast cancer.
Since Lawrence in 2001 proposed the open access (OA) citation advantage, the potential benefit of OA in relation to citation impact has been discussed in depth. The methodology to test this postulate ...ranges from comparing the impact factors of OA journals versus traditional ones, to comparing citations of OA versus non-OA articles published in the same non-OA journals. However, conclusions are not entirely consistent among fields, and two possible explications have been suggested in those fields where a citation advantage has been observed for OA: the early view and the selection bias postulates. In this study, a longitudinal and multidisciplinary analysis of gold OA citation advantage is developed. All research articles in all journals for all subject categories in the multidisciplinary database Web of Science are considered. A total of 1,138,392 articles—60,566 (5.3%) OA articles and 1,077,826 (94.7%) non-OA articles—published in 2009 are analysed. The citation window considered goes from 2009 to 2014, and data are aggregated for the 249 disciplines (subject categories). At journal level, we also study the evolution of journal impact factors for OA and non-OA journals in those disciplines whose OA prevalence is higher (top 36 subject categories). As the main conclusion, there is no generalizable gold OA citation advantage, neither at article nor at journal level.
Summary
Leaf habit has been hypothesized to define a linkage between the slow‐fast plant economic spectrum and the drought resistance‐avoidance trade‐off in tropical forests (‘slow‐safe vs ...fast‐risky’). However, variation in hydraulic traits as a function of leaf habit has rarely been explored for a large number of species.
We sampled leaf and branch functional traits of 97 tropical dry forest tree species from four sites to investigate whether patterns of trait variation varied consistently in relation to leaf habit along the ‘slow‐safe vs fast‐risky’ trade‐off.
Leaf habit explained from 0% to 43.69% of individual trait variation. We found that evergreen and semi‐deciduous species differed in their location along the multivariate trait ordination when compared to deciduous species. While deciduous species showed consistent trait values, evergreen species trait values varied as a function of the site. Last, trait values varied in relation to the proportion of deciduous species in the plant community.
We found that leaf habit describes the strategies that define drought avoidance and plant economics in tropical trees. However, leaf habit alone does not explain patterns of trait variation, which suggests quantifying site‐specific or species‐specific uncertainty in trait variation as the way forward.
The search for long molecular wires that can transport charge with maximum efficiency over many nanometers has driven molecular electronics since its inception. Single-molecule conductance normally ...decays with length and is typically far below the theoretical limit of G 0 (77.5 μS). Here, we measure the conductances of a family of edge-fused porphyrin ribbons (lengths 1–7 nm) that display remarkable behavior. The low-bias conductance is high across the whole series. Charging the molecules in situ results in a dramatic realignment of the frontier orbitals, increasing the conductance to 1 G 0 (corresponding to a current of 20 μA). This behavior is most pronounced in the longer molecules due to their smaller HOMO–LUMO gaps. The conductance-voltage traces frequently exhibit peaks at zero bias, showing that a molecular energy level is in resonance with the Fermi level. This work lays the foundations for long, perfectly transmissive, molecular wires with technological potential.
Genome studies of chronic lymphocytic leukemia (CLL) have revealed the remarkable subclonal heterogeneity of the tumors, but the clinical implications of this phenomenon are not well known. We ...assessed the mutational status of 28 CLL driver genes by deep-targeted next-generation sequencing and copy number alterations (CNA) in 406 previously untreated patients and 48 sequential samples. We detected small subclonal mutations (0.6-25% of cells) in nearly all genes (26/28), and they were the sole alteration in 22% of the mutated cases. CNA tended to be acquired early in the evolution of the disease and remained stable, whereas the mutational heterogeneity increased in a subset of tumors. The prognostic impact of different genes was related to the size of the mutated clone. Combining mutations and CNA, we observed that the accumulation of driver alterations (mutational complexity) gradually shortened the time to first treatment independently of the clonal architecture, IGHV status and Binet stage. Conversely, the overall survival was associated with the increasing subclonal diversity of the tumors but it was related to the age of patients, IGHV and TP53 status of the tumors. In conclusion, our study reveals that both the mutational complexity and subclonal diversity influence the evolution of CLL.
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