46 research outputs found
Effective attraction between oscillating electrons in a plasmoid via acoustic waves exchange
We consider the effective interaction between electrons due to the exchange
of virtual acoustic waves in a low temperature plasma. Electrons are supposed
to participate in rapid radial oscillations forming a spherically symmetric
plasma structure. We show that under certain conditions this effective
interaction can result in the attraction between oscillating electrons and can
be important for the dynamics of a plasmoid. Some possible applications of the
obtained results to the theory of natural long-lived plasma structures are also
discussed.Comment: 14 pages in LaTeX2e, two columns, 3 eps figures; minimal changes,
some typos are corrected; version published on-line in Proc. R. Soc.
Formation of bound states of electrons in spherically symmetric oscillations of plasma
We study spherically symmetric oscillations of electrons in plasma in the
frame of classical electrodynamics. Firstly, we analyze the electromagnetic
potentials for the system of radially oscillating charged particles. Secondly,
we consider both free and forced spherically symmetric oscillations of
electrons. Finally, we discuss the interaction between radially oscillating
electrons through the exchange of ion acoustic waves. It is obtained that the
effective potential of this interaction can be attractive and can transcend the
Debye-Huckel potential. We suggest that oscillating electrons can form bound
states at the initial stages of the spherical plasma structure evolution. The
possible applications of the obtained results for the theory of natural
plasmoids are examined.Comment: 9 pages in LaTeX2e, no figures; paper was significantly modified, 2
new references added, some inessential mathematics was removed, many typos
were corrected; final variant to be published in Physica Script
Containing intense laser light in circular cavity with magnetic trap door
It is shown by particle-in-cell simulation that intense circularly polarized (CP) laser light can be contained in the cavity of a solid-density circular Al-plasma shell for hundreds of light-wave periods before it is dissipated by laser-plasma interaction. A right-hand CP laser pulse can propagate with almost no reflection and attenuation into the cavity through a highly magnetized overdense H-plasma slab filling the entrance hole. The entrapped laser light is then multiply reflected at the inner surfaces of the slab and shell plasmas, slowly losing energy to the latter. Compared to that of the incident laser, the frequency is only slightly broadened and the wave vector slightly modified by the appearance of weak nearly isotropic and homogeneous fluctuations
Tensin3 Is a Negative Regulator of Cell Migration and All Four Tensin Family Members Are Downregulated in Human Kidney Cancer
BACKGROUND: The Tensin family of intracellular proteins (Tensin1, -2, -3 and -4) are thought to act as links between the extracellular matrix and the cytoskeleton, and thereby mediate signaling for cell shape and motility. Dysregulation of Tensin expression has previously been implicated in human cancer. Here, we have for the first time evaluated the significance of all four Tensins in a study of human renal cell carcinoma (RCC), as well as probed the biological function of Tensin3. PRINCIPAL FINDINGS: Expression of Tensin2 and Tensin3 at mRNA and protein levels was largely absent in a panel of diverse human cancer cell lines. Quantitative RT-PCR analysis revealed mRNA expression of all four Tensin genes to be significantly downregulated in human kidney tumors (50-100% reduction versus normal kidney cortex; P<0.001). Furthermore, the mRNA expressions of Tensins mostly correlated positively with each other and negatively with tumor grade, but not tumor size. Immunohistochemical analysis revealed Tensin3 to be present in the cytoplasm of tubular epithelium in normal human kidney sections, whilst expression was weaker or absent in 41% of kidney tumors. A subset of tumor sections showed a preferential plasma membrane expression of Tensin3, which in clear cell RCC patients was correlated with longer survival. Stable expression of Tensin3 in HEK 293 cells markedly inhibited both cell migration and matrix invasion, a function independent of putative phosphatase activity in Tensin3. Conversely, siRNA knockdown of endogenous Tensin3 in human cancer cells significantly increased their migration. CONCLUSIONS: Our findings indicate that the Tensins may represent a novel group of metastasis suppressors in the kidney, the loss of which leads to greater tumor cell motility and consequent metastasis. Moreover, tumorigenesis in the human kidney may be facilitated by a general downregulation of Tensins. Therefore, anti-metastatic therapies may benefit from restoring or preserving Tensin expression in primary tumors
Axl/Gas6/NFÎșB signalling in schwannoma pathological proliferation, adhesion and survival.
TAM family receptor tyrosine kinases comprising Tyro3 (Sky), Axl, and Mer are overexpressed in some cancers, correlate with multidrug resistance and contribute to tumourigenesis by regulating invasion, angiogenesis, cell survival and tumour growth. Mutations in the gene coding for a tumour suppressor merlin cause development of multiple tumours of the nervous system such as schwannomas, meningiomas and ependymomas occurring spontaneously or as part of a hereditary disease neurofibromatosis type 2. The benign character of merlin-deficient tumours makes them less responsive to chemotherapy. We previously showed that, amongst other growth factor receptors, TAM family receptors (Tyro3, Axl and Mer) are significantly overexpressed in schwannoma tissues. As Axl is negatively regulated by merlin and positively regulated by E3 ubiquitin ligase CRL4DCAF1, previously shown to be a key regulator in schwannoma growth we hypothesized that Axl is a good target to study in merlin-deficient tumours. Moreover, Axl positively regulates the oncogene Yes-associated protein, which is known to be under merlin regulation in schwannoma and is involved in increased proliferation of merlin-deficient meningioma and mesothelioma. Here, we demonstrated strong overexpression and activation of Axl receptor as well as its ligand Gas6 in human schwannoma primary cells compared to normal Schwann cells. We show that Gas6 is mitogenic and increases schwannoma cell-matrix adhesion and survival acting via Axl in schwannoma cells. Stimulation of the Gas6/Axl signalling pathway recruits Src, focal adhesion kinase (FAK) and NFÎșB. We showed that NFÎșB mediates Gas6/Axl-mediated overexpression of survivin, cyclin D1 and FAK, leading to enhanced survival, cell-matrix adhesion and proliferation of schwannoma. We conclude that Axl/FAK/Src/NFÎșB pathway is relevant in merlin-deficient tumours and is a potential therapeutic target for schwannoma and other merlin-deficient tumours
Etiologia viral e bacteriana de casos de gastroenterite infantil: uma caracterização clĂnica
âIf itâs a medical issue I would have covered it by nowâ: learning about fibromyalgia through the hidden curriculum: a qualitative study
Overcoming the barriers to the diagnosis and management of chronic fatigue syndrome/ME in primary care: a meta synthesis of qualitative studies
Listen to Me : Parentsâ Satisfaction with Special Needs Services in Syria â A Descriptive and Exploratory Study
Parentsâ involvement in their childâs educational and therapy choices is an important aspect of their therapy. This involvement may be related to their satisfaction with their childâs service providersâ direct child services family-related involvement. Additionally, civil unrest may influence parentsâ satisfaction. For example, the Syrian civil war, which began in 2011, has influenced families with children in schools, and specifically children who have disabilities. The purpose of this descriptive and exploratory study was to investigate parentsâ perceptions of current services provided in Syria for their children with disabilities, and to identify the services provided to Syrian children with ASD and other developmental disabilities. A total of 466 parents completed the studyâs survey, with about half of the participants reporting that their child received early intervention and fewer that their child received other therapies (e.g., speech, behavioral, counseling). Parents also reported feeling unwelcome to contribute to their childâs individualized education program (IEP), and were not satisfied with the services their child received. In addition, some demographic factors, such as place of residence, the childâs current age, the childâs diagnosis, the childâs attending age at school, and which program the child was enrolled in, increased the parentsâ satisfaction level. Implications and future research are discussed. Highlights Parentsâ involvement can negatively or positively impact parentsâ engagement in their childrenâs education. Receiving services in unordinary circumstances, such as during the civil war, impacts parentsâ sense of satisfaction. The programs used acceptable methods and focused on behaviors that are important to families. Parents were dissatisfied with the safety precautions taken at school. Staff should provide a structured environment in order to be able to manage studentsâ behaviors
Special Education in Syria : Challenges and Recommendations, a Descriptive Study
Over the past three decades, various efforts have been made to develop special education policies and services in Syria. However, to guarantee the improvement of special education services and to develop sustainable national enhancements during both the emergency and reconstruction phases of the Syrian Civil War, it is necessary to continue to address the intersectional ways by which people with disabilities have been disproportionately impacted. This paper provides an update on disability and special education in Syria, including a brief account of the historical development of, impact of the civil war on, and major current challenges for the field of special education. These challenges include, but are not limited to, inadequate financial resources, a scarcity of integration programs, negative social attitudes because of a lack of knowledge, limited accessibility to services, and barriers to appropriate disability programmes. Recommendations for action are also offered. Further, we provide suggestions to improve special-education services for people with disabilities in Syria, as well as to develop sustainable national improvements for them