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OALib Journal期刊

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匹配条件: “Umansky” ,找到相关结果约104条。
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La regulación de la conducta en las relaciones de consumo
Umansky,Sandra Natalia;
Enfoques , 2009,
Abstract: the behavior of business men and consumers is regulated by a cluster of rules that make up a framework of guidelines for the way they should act. that framework of law formulates norms of logical and axiological should be, like technical rules of marketing, ethics of corporate responsibility and legal standards that prescribes consumers law. this article pretends to describe them and remark the way this coincident should be is transgressed by behaviors indeed executed by suppliers and consumers.
Myeloid-Derived Suppressor Cells Interact with Tumors in Terms of Myelopoiesis, Tumorigenesis and Immunosuppression: Thick as Thieves
Alexandra Sevko, Viktor Umansky
Journal of Cancer , 2013,
Abstract: Tumor progression is often associated with chronic inflammation in the tumor microenvironment, which is mediated by numerous cytokines, chemokines and growth factors produced by cancer and stroma cells. All these mediators support tumor development and immunosuppression in autocrine and/or paracrine ways. Neutralization of chronic inflammatory conditions can lead to the restoration of anti-tumor immune responses. Among stroma cells infiltrating tumors, myeloid-derived suppressor cells (MDSCs) represent one of the most important players mediating immunosuppression. These cells may not only inhibit an anti-tumor immunity but also directly stimulate tumorigenesis as well as tumor growth and expansion. Therefore, understanding the mechanisms of generation, migration to the tumor site and activation of MDSC is necessary for the development of new strategies of tumor immunotherapy.
Presenting Survey Items One at a Time Compared to All at Once Decreases Missing Data without Sacrificing Validity in Research with Internet Volunteers
Brian A. Nosek, N. Sriram, Emily Umansky
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036771
Abstract: In two large web-based studies, across five distinct criteria, presenting survey items one-at-a-time was psychometrically either the same or better than presenting survey items all-at-once on a single web page to volunteer participants. In the one-at-a-time format, participants were no more likely to drop-out of the study (Criterion 1), and were much more likely to provide answers for the survey items (Criterion 2). Rehabilitating participants who otherwise would not have provided survey responses with the one-at-a-time format did not damage internal consistency of the measures (Criterion 3) nor did it negatively affect criterion validity (Criterion 4). Finally, the one-at-a-time format was more efficient with participants completing it more quickly than the all-at-once format (Criterion 5). In short, the one-at-a-time format results in less missing data with a shorter presentation time, and ultimately more power to detect relations among variables.
The characteristic of the vegetative land cover of the Kaliningrad peninsula ecosystems
Kurkina M.,Dedkov V.,Umansky A.
Vestnik Immanuel Kant Baltic Federal University , 2013,
Abstract: This article offers an ecological analysis of natural ecosystems used in the monitoring of the microflora of soil lands. The authors characterize the soilvegetation cover of the ecosystems of the Kaliningrad Peninsula. The difference in the species composition of phytocenoses and their environmental conditions is identified.
The morphological structure of the soils of the Kaliningrad peninsula natural ecosystems
Umansky A.,Kurkina M.,Dedkov V.
Vestnik Immanuel Kant Baltic Federal University , 2013,
Abstract: This article describes the soil mantle of the natural ecosystems of the Kaliningrad peninsula. The authors offer experimental data on the morphology structure and pH of the soils.
Scattering of Bunched Fractionally Charged Quasiparticles
Y. C. Chung,M. Heiblum,V. Umansky
Physics , 2003, DOI: 10.1103/PhysRevLett.91.216804
Abstract: The charge of fractionally charged quasiparticles, proposed by Laughlin to explain the fractional quantum Hall effect (FQHE), was recently verified by measurements. Charge q=e/3 and e/5 (e is the electron charge), at filling factors nu=1/3 and 2/5, respectively, were measured. Here we report the unexpected bunching of fractional charges, induced by an extremely weak backscattering potential at exceptionally low electron temperatures (T<10 mK) - deduced from shot noise measurements. Backscattered charges q=nu e, specifically, q=e/3, q=2e/5, and q<3e/7, in the respective filling factors, were measured. For the same settings but at an only slightly higher electron temperature, the measured backscattered charges were q=e/3, q=e/5, and q=e/7. In other words, bunching of backscattered quasiparticles is taking place at sufficiently low temperatures. Moreover, the backscattered current exhibited distinct temperature dependence that was correlated to the backscattered charge and the filling factor. This observation suggests the existence of 'low' and 'high' temperature backscattering states, each with its characteristic charge and characteristic energy.
Autochthonous Mouse Melanoma and Mammary Tumors do not Express the Pluripotency Genes Oct4 and Nanog
Caroline Schreiber, Vanessa Kuch, Viktor Umansky, Jonathan P. Sleeman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057465
Abstract: The homeodomain transcription factors Oct4 and Nanog maintain pluripotency and self-renewal in embryonic stem cells. In somatic cells, inappropriate expression of these genes has been associated with loss of differentiation, malignant transformation, and the acquisition of cancer stem cell-like properties. As cancer stem cells have been suggested to underlie the growth and malignancy of tumors, Oct4 and Nanog may represent therapeutic targets. Their expression could also act as a marker of the cancer stem cell population, permitting its isolation and characterisation. Nevertheless, the existence of multiple pseudogenes and isoforms of these genes has complicated the interpretation of the data that supports a role for Oct4 and Nanog in the cancer context. Here we addressed this issue using knockin mice in which IRES elements are used to allow GFP expression under the control of the endogenous Oct4 or Nanog promoters, while maintaining correct expression of the Oct4 or Nanog gene. These mice were crossed with MT/ret mice that develop melanomas, and with MMTV-PyMT mice and MMTV-Neu mice that develop mammary adenocarcinomas. We analysed the tumors that developed in these compound mice for GFP expression. In this way we could assess transcription of Oct4 and Nanog in autochthonous cancers without the complication of factors such as pseudogene expression, alternative splicing and antibody specificity. Both the Oct4 and Nanog knockin tumor-bearing mice expressed GFP in blastocysts and testes as expected. However, we could find no evidence for expression of the GFP reporter above background levels in tumors using FACS, qPCR and immunohistochemistry. Furthermore, cultivation of Oct4GFP and NanogGFP MMTV-PyMT tumor cells either adherently or as spheroids had no effect on the expression of the GFP reporter. Together these data suggest that Oct4 and Nanog are not expressed in tumor cells that arise in the autochthonous cancer models studied here.
Shot Noise and Fractional Charge at the 2/3 Composite Fractional Edge Channel
Aveek Bid,Nissim Ofek,Moty Heiblum,Vladimir Umansky,Diana Mahalu
Physics , 2009,
Abstract: The exact structure of edge modes in `hole conjugate' fractional quantum Hall states remains an unsolved issue despite significant experimental and theoretical efforts devoted to their understanding. Recently, there has been a surge of interest in such studies led by the search for neutral modes, which in some cases may lead to exotic statistical properties of the excitations. In this letter we report on detailed measurements of shot noise, produced by partitioning of the more familiar 2/3 state. We find a fractional charge of (2/3)e at the lowest temperature, decreasing to e/3 at an elevated temperature. Surprisingly, strong shot noise had been measured on a clear 1/3 plateau upon partitioning the 2/3 state. This behavior suggests an uncommon picture of the composite edge channels quite different from the accepted one.
Effect of Ka-band Microwave on the spin dynamics of electrons in a GaAs/Al0.35Ga0.65As heterostructure
Haihui Luo,Xuan Qian,Xiaofang Gu,Yang Ji,V. Umansky
Physics , 2009, DOI: 10.1063/1.3138154
Abstract: We report experimental results of the effect of Ka-band microwave on the spin dynamics of electrons in a 2D electron system in a GaAs/Al0.35Ga0.65As heterostructure, via time-resolved Kerr rotation measurements. While the microwave reduces the transverse spin lifetime of the bulk GaAs when its frequency is close to the Zeeman splitting of the electrons in the magnetic field, it significantly increases that of electrons in the 2D electron system, from 745 ps to 1213 ps. Such a microwave-enhanced spin lifetime is ascribed to the microwave-induced electron scattering which leads to a motional narrowing of spins via DP mechanism.
Dephasing due to Which Path Detector
E. Buks,R. Schuster,M. Heiblum,D. Mahalu,V. Umansky
Physics , 1997, DOI: 10.1016/S0921-4526(98)00118-5
Abstract: We study dephasing of electrons induced by a which path detector and thus verify Bohr's complementarity principle for fermions. We utilize a double path interferometer with two slits, with one slit being replaced by a coherent quantum dot (QD). A short one dimensional channel, in the form of a quantum point contact (QPC), in close proximity to the QD, serves as a which path detector. We find that by varying the properties of the QPC detector we affect the visibility of the interference, inducing thus dephasing. We develop a simple model to explain the dephasing due to the nearby detector and find good agreement with the experiment.
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