ABSTRACT Emission from neutron stars and accretion disks in low-mass X-ray binaries is anisotropic. The non-spherical shape of the disk as well as blocking of the neutron star by the disk make the ...observed flux dependent on the inclination angle of the disk with respect to the line of sight. This is of importance for the interpretation of thermonuclear X-ray bursts from neutron stars. Because part of the X-ray burst is reflected off the disk, the observed burst flux depends on the anisotropies for both direct emission from the neutron star and reflection off the disk. This influences measurements of source distance, mass accretion rate, and constraints on the neutron star's equation of state. Previous predictions of the anisotropy factors assumed a geometrically flat disk. Detailed observations of two so-called superbursts allowed for the direct and the reflected burst fluxes to each be measured separately. The reflection fraction was much higher than what the anisotropies of a flat disk can account for. We create numerical models to calculate the anisotropy factors for different disk shapes, including concave disks. We present the anisotropy factors of the direct and reflected burst fluxes separately, as well as the anisotropy of the persistent flux. Reflection fractions substantially larger than unity are produced in the case where the inner accretion disk increases steeply in height, such that part of the star is blocked from view. Such a geometry could possibly be induced by the X-ray burst if X-ray heating causes the inner disk to puff up.
Osteosarcoma (OS) is the most common primary malignancy of bone. There is a critical need to identify the events that lead to the poorly understood mechanism of OS development and metastasis. The ...goal of this investigation is to identify and characterize a novel marker of OS progression. We have established and characterized a highly metastatic OS subline that is derived from the less metastatic human MG63 line through serial passages in nude mice via intratibial injections. Microarray analysis of the parental MG63, the highly metastatic MG63.2 subline, as well as the corresponding primary tumors and pulmonary metastases revealed insulin-like growth factor binding protein 5 (IGFBP5) to be one of the significantly downregulated genes in the metastatic subline. Confirmatory quantitative RT-PCR on 20 genes of interest demonstrated IGFBP5 to be the most differentially expressed and was therefore chosen to be one of the genes for further investigation. Adenoviral mediated overexpression and knockdown of IGFBP5 in the MG63 and MG63.2 cell lines, as well as other OS lines (143B and MNNG/HOS) that are independent of our MG63 lines, were employed to examine the role of IGFBP5. We found that overexpression of IGFBP5 inhibited in vitro cell proliferation, migration and invasion of OS cells. Additionally, IGFBP5 overexpression promoted apoptosis and cell cycle arrest in the G1 phase. In an orthotopic xenograft animal model, overexpression of IGFBP5 inhibited OS tumor growth and pulmonary metastases. Conversely, siRNA-mediated knockdown of IGFBP5 promoted OS tumor growth and pulmonary metastases in vivo. Immunohistochemical staining of patient-matched primary and metastatic OS samples demonstrated decreased IGFBP5 expression in the metastases. These results suggest 1) a role for IGFBP5 as a novel marker that has an important role in the pathogenesis of OS, and 2) that the loss of IGFBP5 function may contribute to more metastatic phenotypes in OS.
It has been shown that the exposure to airborne particulate matter is one of the most significant environmental risks people face. Since indoor environment is where people spend the majority of time, ...in order to protect against this risk, the origin of the particles needs to be understood: do they come from indoor, outdoor sources or both? Further, this question needs to be answered separately for each of the PM mass/number size fractions, as they originate from different sources. Numerous studies have been conducted for specific indoor environments or under specific setting. Here our aim was to go beyond the specifics of individual studies, and to explore, based on pooled data from the literature, whether there are generalizable trends in routes of exposure at homes, schools and day cares, offices and aged care facilities. To do this, we quantified the overall 24h and occupancy weighted means of PM10, PM2.5 and PN - particle number concentration. Based on this, we developed a summary of the indoor versus outdoor origin of indoor particles and compared the means to the WHO guidelines (for PM10 and PM2.5) and to the typical levels reported for urban environments (PN). We showed that the main origins of particle metrics differ from one type of indoor environment to another. For homes, outdoor air is the main origin of PM10 and PM2.5 but PN originate from indoor sources; for schools and day cares, outdoor air is the source of PN while PM10 and PM2.5 have indoor sources; and for offices, outdoor air is the source of all three particle size fractions. While each individual building is different, leading to differences in exposure and ideally necessitating its own assessment (which is very rarely done), our findings point to the existence of generalizable trends for the main types of indoor environments where people spend time, and therefore to the type of prevention measures which need to be considered in general for these environments.
•Exposure to airborne particles is a significant risk factor.•Previous studies assessed it for specific buildings or particle metrics.•This work explored existence of generalizable trends based on published literature.•PM10, PM2.5, PNC at homes, schools, offices, aged care facilities were considered.•The general trends identified are pointers to the necessary prevention measures.
Collective behavior can spontaneously emerge when individuals follow common rules of interaction. However, the behavior of each individual differs due to existing genetic and non-genetic variation ...within the population. It remains unclear how this individuality is managed to achieve collective behavior. We quantify individuality in bands of clonal Escherichia coli cells that migrate collectively along a channel by following a self-generated gradient of attractant. We discover that despite substantial differences in individual chemotactic abilities, the cells are able to migrate as a coherent group by spontaneously sorting themselves within the moving band. This sorting mechanism ensures that differences between individual chemotactic abilities are compensated by differences in the local steepness of the traveling gradient each individual must navigate, and determines the minimum performance required to travel with the band. By resolving conflicts between individuality and collective migration, this mechanism enables populations to maintain advantageous diversity while on the move.
It has been reported that the miR-106b∼25 cluster, a paralog of the miR-17∼92 cluster, possesses oncogenic activities. However, the precise role of each microRNA (miRNA) in the miR-106b∼25 cluster is ...not yet known. In this study, we examined the function of miR-93, one of the microRNAs within the miR-106b∼25 cluster, in angiogenesis and tumor formation. We found that miR-93 enhanced cell survival, promoted sphere formation and augmented tumor growth. Most strikingly, when miR-93-overexpressing U87 cells were co-cultured with endothelial cells, they supported endothelial cell spreading, growth, migration and tube formation. In vivo studies revealed that miR-93-expressing cells induced blood vessel formation, allowing blood vessels to extend to tumor tissues in high densities. Angiogenesis promoted by miR-93 in return facilitated cell survival, resulting in enhanced tumor growth. We further showed that integrin-β8 is a target of miR-93. Higher levels of integrin-β8 are associated with cell death in tumor mass and in human glioblastoma. Silencing of integrin-β8 expression using small interfering RNA promoted cell proliferation, whereas ectopic expression of integrin-β8 decreased cell growth. These findings showed that miR-93 promotes tumor growth and angiogenesis by suppressing, at least in part, integrin-β8 expression. Our results suggest that inhibition of miR-93 function may be a feasible approach to suppress angiogenesis and tumor growth.
Motivated by the recent development of phase field methods for modeling and simulating the fracture of brittle and quasi-brittle materials, a general approach is proposed to decompose the ...infinitesimal strain tensor (or Cauchy stress tensor) into a positive part and a negative part which are orthogonal in the sense of an inner product where the elastic stiffness (or compliance) tensor acts as a metric. This approach is based on a strain (or stress) transformation preserving the elastic energy, and gives rise to a generalized Pythagorean theorem. It is valid not only for the isotropic elastic case but also for all the anisotropic ones. Decompositions of the strain (or stress) tensor are given in a coordinate-free way. The main results obtained are illustrated and detailed for the elastic isotropic case in an analytical explicit manner.
•Coordinate-free decomposition of the strain tensor into positive and negative parts.•The elastic tensor acting as a metric for defining the orthogonality.•The strain orthogonal decomposition valid for all elastic symmetry classes.
Graphene-based van der Waals (vdW) heterostructures composed of two-dimensional transition metal dichalcogenides (TMDs) and graphene show great potential in the design and manufacture of field effect ...transistors. However, the Schottky barrier generated by the contact between metal and semiconductor hinders the conduction of electrons, so it is necessary to effectively adjust the Schottky barrier and form a low-resistance Ohmic contact. Based on first-principles calculations, graphene/WSSe (G/WSSe) heterostructures have been established and the corresponding electronic properties have been studied. Firstly, these heterostructures form an n-type Schottky contact with a SBH of 0.35 eV and a p-type Schottky contact with a SBH of 0.66 eV at their respective interfaces. In addition, the Schottky contact can be significantly adjusted by changing the interlayer coupling or applying an external biaxial strain, and an Ohmic contact could also be formed under the biaxial strain. This study not only offers a basic understanding of G/WSSe heterostructures, but also provides a reference for the application of G/WSSe heterostructures in optoelectronic and nanoelectronic devices.
Graphene-based van der Waals (vdW) heterostructures composed of two-dimensional transition metal dichalcogenides (TMDs) and graphene show great potential in the design and manufacture of field effect transistors.
With the aggravation of environmental pollution and the energy crisis, it is particularly important to develop and design environment-friendly and efficient spontaneous enhanced visible-light-driven ...photocatalysts for water splitting. Herein novel type-II van der Waals (vdW) GaSe/CN and Ga2SSe/CN heterostructures are proposed through first-principles calculations. Their electronic properties and photocatalytic performance are theoretically analyzed. In particular, their appropriate band gap and band-edge position meet the requirements of the oxygen evolution reaction, and the reaction is thermodynamically feasible in most pH ranges. The unique band alignment of these heterostructured photocatalysts leads to high solar-to-hydrogen energy conversion efficiencies up to 15.11%, which has a good commercial application prospect. More excitingly, with the application of 2% biaxial strain, the smooth progress of the water-splitting reaction of the GaSe/CN and Ga2SSe/CN heterostructures can still be maintained, and the carrier mobility and optical absorption characteristics can be effectively improved. Consequently, these findings suggest that the GaSe/CN and Ga2SSe/CN vdW heterostructures have promising potentials as photocatalysts for water splitting. This work may provide a promising clue for the design of efficient and stable photocatalytic water-splitting catalysts under visible spectroscopy.
Summary
Background
Acne is a complex and multifactorial skin disorder. Alterations in skin surface lipid (SSL) are believed to be an important factor in the pathogenesis of acne and SSL plays a key ...role in the initiation of acne lesions.
Objectives
To analyse the lipidome profiles of SSL in patients with acne and in healthy controls in order to understand SSL abnormity in acne in young men.
Methods
Ultraperformance liquid chromatography‐quadrupole time‐of‐flight mass spectrometry (UPLC‐QTOF‐MS) and multivariate data analysis were used to investigate the SSL variations in main lipid classes, subclasses and individual species.
Results
Results showed that there were significant differences in the lipidome between the two groups. Significantly increased levels of three main classes of glycerophospholipids, fatty acyls and sterol lipids and significantly decreased levels of two main classes of prenol lipids and saccharolipids were observed in patients with acne. Subsequent analysis showed that there were 18 subclasses, which varied significantly and shared the same changing trends of the main classes to which they belonged. Multivariate data analysis indicated that 36 individual species were mostly responsible for this discrimination and the majority of differentiating lipid species were phosphatidylserines. Furthermore, it was observed that the chain length of ceramides were reduced and unsaturated free fatty acids were increased in patients with acne.
Conclusions
SSL sampled from young male patients with acne had significantly higher levels of phosphatidylserines. Additionally, the reduction in the chain length of ceramides and the increase in unsaturated free fatty acids contributed to an altered lipid organization and decreased skin barrier function in acne.
What's already known about this topic?
Modifications in skin surface lipid (SSL) are believed to be one of the most critical factors in the pathogenesis of acne.
Cholesterol, wax esters and squalene are present in the SSL of patients with acne at higher levels than in controls, whereas lower levels of linoleic acid (and its precursor) have been reported in patients with acne.
A decreased skin barrier function is an important feature of acne.
What does this study add?
In SSL samples from patients with acne and controls, phosphatidylserines were the most common differentiating lipid species.
Exposure to phosphatidylserines could be an important event involved in the inflammation and apoptosis of acne lesions.
The reduction in the chain length of ceramides and the increase in unsaturated free fatty acids contributes to an altered lipid organization and decreased skin barrier function in acne.
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