486 research outputs found

    Contracts Concluded by Electronic Agents - Comparative Analysis of American and Polish Legal Systems

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    This article analyzes the US and Polish law on contract formation by electronic agents. It persents the main similarities and differences in the approaches of common and civil legal systems. Finally, it discusses changes in legal theories in Poland that had to be made in order to comply with standards of electronic commerce

    Реалізація когнітивної психології у вихованні маленької дитини. (Implementation of cognitive psychology in the education a young child.)

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    Основною метою науково-дослідних міркувань автора є аналіз застосування когнітивної психологіїу вихованні маленької дитини. Більш детально були пояснені такі питання: Чи використовуються теоретичні знання когнітивної психології в освітній практиці? Який тип шкільного знання домінує у вихованні маленької дитини? Чи враховує рання освіта аспекти формування загальної структури психіки та особистості дитини віком 6-7 і 9-10 років? У цей період формування психіки є дуже еластичним і чутливим до освітніх взаємодій. Безсумнівно, сутність дидактичного та виховного процесу також значно відповідає характеру відносини, що виникають між учасниками цих взаємодій. Таким чином, увага приділяється тому, що диктує освітній контекст для збереження балансу між суб'єктивністю учня - потенціал, і суб'єктивності вчителя - наставника. У дидактично-виховному процесі матеріалізація ідеї суб'єктивності учнів - мета повинна бути реалізована відповідно до суб'єктивністі іншого індивіда. Дидактичний та виховний процес розуміється як такий, де 1-й рівень освіти вимагає перевірки системного підходу і теоретичної основи складових для подальшого обґрунтування проекту змін та дії. Для сучасної шкільної освіти особливий сенс мають праці великих науковців, таких як: Ж.Піаже, Л. Виготський та Дж. Брунер. (The main objective of the scientific and research considerations undertaken by the author is the analysis of the application of cognitive psychology in the education of a small child. The following questions were explained in more detail regarding the above key problem: Does a theoretical knowledge from within the cognitive psychology permeate educational practice? Which type of school knowledge dominates in the education of a small child? Early school education covers children aged 6-7 and 9-10 andfalls within the period of shaping overall structures of the psychics and personality of a child. During that period it is very elastic and prone to educational interactions. Undoubtedly, the essence of the course of the didactic and educational process also strongly corresponds with the character of relations occurring between participants of these interactions. Therefore, the attention is paid to the fact that the said educational context enables keeping balance between the subjectivity of a pupil - charge and the subjectivity of a teacher - tutor. In the didactic and educational process the materialisation of the idea of subjectivity ofpupils -charges should be realised in agreement with the subjectivity of another man. The didactic and educational process understood in such a way on the 1st level of education requires verification of the hither to systematic approach and theoretical bases constituting the justification of drafted changes and actions undertaken. For contemporary school education the concepts of such great scientists gain a special meaning: J. Piaget, L. Wygotski or J. Bruner.

    Fractionation of MG Isotopes between the Sun’s Photosphere and the Solar Wind

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    The Genesis mission goal is to precisely determine the elemental and isotopic composition of the solar photosphere through measurements of solar wind; the photospheric composition being a proxy for the early solar nebula. So, how elements and isotopes are fractionated (or not) when accelerated out of the photosphere is fundamental to interpreting Genesis data

    HLA-DO modulates the diversity of the MHC-II self-peptidome

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    Presentation of antigenic peptides on MHC-II molecules is essential for tolerance to self and for initiation of immune responses against foreign antigens. DO (HLA-DO in humans, H2-O in mice) is a non-classical MHC-II protein that has been implicated in control of autoimmunity and regulation of neutralizing antibody responses to viruses. These effects likely are related to a role of DO in selecting MHC-II epitopes, but previous studies examining the effect of DO on presentation of selected CD4 T cell epitopes have been contradictory. To understand how DO modulates MHC-II antigen presentation, we characterized the full spectrum of peptides presented by MHC-II molecules expressed by DO-sufficient and DO-deficient antigen-presenting cells in vivo and in vitro using quantitative mass spectrometry approaches. We found that DO controlled the diversity of the presented peptide repertoire, with a subset of peptides presented only when DO was expressed. Antigen-presenting cells express another non-classical MHC-II protein, DM, which acts as a peptide editor by preferentially catalyzing the exchange of less stable MHC-II peptide complexes, and which is inhibited when bound to DO. Peptides presented uniquely in the presence of DO were sensitive to DM-mediated exchange, suggesting that decreased DM editing was responsible for the increased diversity. DO-deficient mice mounted CD4 T cell responses against wild-type antigen-presenting cells, but not vice versa, indicating that DO-dependent alterations in the MHC-II peptidome could be recognized by circulating T cells. These data suggest that cell-specific and regulated expression of HLA-DO serves to fine-tune MHC-II peptidomes, to enhance self-tolerance to a wide spectrum of epitopes while allowing focused presentation of immunodominant epitopes during an immune response

    Influence of acoustic cavitation on the controlled ultrasonic dispersion of carbon nanotubes.

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    Ultrasonication is the most widely used technique for the dispersion of a range of nanomaterials, but the intrinsic mechanism which leads to stable solutions is poorly understood with procedures quoted in the literature typically specifying only extrinsic parameters such as nominal electrical input power and exposure time. Here we present new insights into the dispersion mechanism of a representative nanomaterial, single-walled carbon nanotubes (SW-CNTs), using a novel up-scalable sonoreactor and an in situ technique for the measurement of acoustic cavitation activity during ultrasonication. We distinguish between stable cavitation, which leads to chemical modification of the surface of the CNTs, and inertial cavitation, which favors CNT exfoliation and length reduction. Efficient dispersion of CNTs in aqueous solution is found to be dominated by mechanical forces generated via inertial cavitation, which in turn depends critically on surfactant concentration. This study highlights that careful measurement and control of cavitation rather than blind application of input power is essential in the large volume production of nanomaterial dispersions with tailored properties

    Development of Chemical and Mechanical Cleaning Procedures for Genesis Solar Wind Samples

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    The Genesis mission was the only mission returning pristine solar material to Earth since the Apollo program. Unfortunately, the return of the spacecraft on September 8, 2004 resulted in a crash landing shattering the solar wind collectors into smaller fragments and exposing them to desert soil and other debris. Thorough surface cleaning is required for almost all fragments to allow for subsequent analysis of solar wind material embedded within. However, each collector fragment calls for an individual cleaning approach, as contamination not only varies by collector material but also by sample itself

    ToF-SIMS Investigation of the Effectiveness of Acid-Cleaning procedures for Genesis Solar Wind Collectors

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    ToF-SIMS images of Genesis sample surfaces contain an incredible amount of important information, but they also show that the crash-derived surface contamination has many components, presenting a challenge to cleaning. Within the variability, we have shown that there are some samples which appear to be clean to begin with, e.g. 60471, and some are more contaminated. Samples 60493 and 60500 are a part of a focused study of the effectiveness of aqua regia and/or sulfuric acid cleaning of small flight Si implanted with Li-6 using ToF-SIMS

    Three Proposed Compendia for Genesis Solar Wind Samples: Science Results, Collector Materials Characterization and Cleaning Techniques

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    Final Paper and not the abstract is attached. Introduction: Planetary material and cosmochemistry research using Genesis solar wind samples (including the development and implementation of cleaning and analytical techniques) has matured sufficiently that compilations on several topics, if made publically accessible, would be beneficial for researchers and reviewers. We propose here three compendia based on content, organization and source of documents (e.g. published peer-reviewed, published, internal memos, archives). For planning purposes, suggestions are solicited from potential users of Genesis solar wind samples for the type of science content and/or organizational style that would be most useful to them. These compendia are proposed as living documents, periodically updated. Similar to the existing compendia described below, the curation compendia are like library or archival finding aids, they are guides to published or archival documents and should not be cited as primary sources

    Inactivating mutations and X-ray crystal structure of the tumor suppressor OPCML reveal cancer-associated functions

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    OPCML, a tumor suppressor gene, is frequently silenced epigenetically in ovarian and other cancers. Here we report, by analysis of databases of tumor sequences, the observation of OPCML somatic missense mutations from various tumor types and the impact of these mutations on OPCML function, by solving the X-ray crystal structure of this glycoprotein to 2.65 A resolution. OPCML consists of an extended arrangement of three immunoglobulin-like domains and homodimerizes via a network of contacts between membrane-distal domains. We report the generation of a panel of OPCML variants with representative clinical mutations and demonstrate clear phenotypic effects in vitro and in vivo including changes to anchorage-independent growth, interaction with activated cognate receptor tyrosine kinases, cellular migration, invasion in vitro and tumor growth in vivo. Our results suggest that clinically occurring somatic missense mutations in OPCML have the potential to contribute to tumorigenesis in a variety of cancers
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