579 research outputs found
Chiral tetranuclear and dinuclear copper(II) complexes for TEMPO-mediated aerobic oxidation of alcohols : are four metal centres better than two?
Get PDFThe one-pot reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde, (R)-2-aminoglycinol and Cu(OAc)2·2H2O in a 1 : 1 : 1 ratio in the presence of triethylamine led to the isolation of X-ray quality crystals of the chiral complex (R)-1 in high yield. The single crystal structure of (R)-1 reveals a tetranuclear copper(II) complex that contains a {Cu4(μ-O)2(μ3-O)2N4O4} core. A reaction using (1S,2R)-2-amino-1,2-diphenylethanol as precursor under the same conditions generated the chiral complex (S,R)-2; its structure was determined by single crystal X-ray crystallography and was found to contain a {Cu2(μ-O)2N2O2} core. Both (R)-1 and (S,R)-2 have been used for catalytic aerobic oxidation of benzylic alcohols in combination with the TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) radical. (R)-1 selectively catalyses the conversion of various aromatic primary alcohols to the corresponding aldehydes with high yields (99%) and TONs (770) in the air, while (S,R)-2 exhibits less promising catalytic performance under the same reaction conditions. The role of the cluster structures in (R)-1 and (S,R)-2 in controlling the reactivity towards aerobic oxidation reactions is discussed
Heavy meson production at HERA
No full textThe copious production of charm mesons at HERA has allowed QCD to be probed in open charm and charm vector meson production. Elastic and proton-dissociatve photoproduction of J/ψ mesons have been measured at HERA. The data are compared to other measurements and the W and t dependences are parametrised using phenomenological fits. The ψ (2S) state has also been measured exclusively and the ratio of its production rate to J/ψ mesons presented as a function of the kinematic variables. Inelastic production of J/ψ and ψ(2S) mesons gives insight into non-relativistic QCD and final results are presented here. Open charm production has been measured in order to better understand the fragmentation process of charm mesons as well as giving insight into the structure of the proton
Toward better regulation of private pension funds
Get PDFThe author analyzes the typical model for regulating investments in private pension funds. Pension reforms like those pioneered by Chile are being initiated or considered in Argentina, Bolivia, China, Colombia, Costa Rica, Hungary, Mexico, Peru, Uruguay, and elsewhere. Such reforms greatly improve fiscal discipline, make social security benefits and burdens equitable, and deepen financial markets. But they are also typically accompanied by: tight restrictions on the investments in pension fund portfolios; restrictions on the management of mandated retirement savings (to newly created legal entities called pension administrators, to the exclusion of such financial intermediaries as banks and mutual funds); minimum-return guarantees from the state and/or pension funds; and commissions based on salary rather than on the volume of assets managed. Illustrating his conclusions with case studies from Chile and Peru, the author shows that these restrictions, though well-meant, are poorly justified by financial theory, distort incentives for competition based on product choice and efficiency, increase administrative costs, and seriously reduce the affiliates'appropriate risk-return choices and returns. And the resulting potential losses in retirement income are great. The author recommends a significant departure from the Chilean-style model of a private pension fund system. He briefly describes implementation and transition issues for the alternative system that he proposes, which would: permit diverse intermediaries -including banks and mutual funds that meet appropriate prudential standards- to manage retirement savings; allow a greater choice between investment products; require that returns be reported on a net basis; and charge commissions as a fraction of assets managed.Payment Systems&Infrastructure,Economic Theory&Research,International Terrorism&Counterterrorism,Environmental Economics&Policies,Insurance&Risk Mitigation,Pensions&Retirement Systems,Environmental Economics&Policies,Insurance&Risk Mitigation,Banks&Banking Reform,Economic Theory&Research
Hair Symbolism in the Polish Folk Culture
Get PDFOf all the elements of the human body, hair has been one of the most well-developed symbols. It has been the subject of a variety of activities to which many meanings have been assigned. A specific hairstyle, its shape, length, weave or color in different cultures have meant belonging to particular social groups or determining economic or social status. The author focuses her attention on the aspects of folk rituals using hair, including the symbolic meaning of manipulation of hair, such as combing, pinning and cutting. In addition to determining social status, the important role in the ritual’s calendar and family life, hair has been associated with broadly understood symbolism and various meanings. The purpose of the text is to also show the relationship between the belief function and the appearance of the hair and the actions by which they are affected
On Holomorphic Mappings with Compact Type Range
Get PDFUsing Mujica’s linearization theorem, we extend to the holomorphic setting some classical characterizations of compact (weakly compact, Rosenthal, Asplund) linear operators between Banach spaces such as the Schauder, Gantmacher and Gantmacher–Nakamura theorems and the Davis–Figiel–Johnson–Pełczynski, Rosenthal and Asplund factorization theorems.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The first author was partially supported by project UAL-FEDER Grant UAL2020-FQM-B1858, by Junta de Andalucía Grants P20-00255 and FQM194, and by Ministerio de Ciencia e Innovación Grant PID2021-122126NB-C31. The third author was also supported by PGC2018-097960-B-C22 (MCIU/AEI/ERDF, UE)
What will be the possible impact of sharing platforms on the labour market?
No full textThe creation and usage of digital platforms is not only increasing in the private sector but also
in the public one. There is much contention about the impact of digitalization on employment, social
structures, public policies, as well as on entrepreneurial initiative and business. Although some
early reviews opposed the imposition of heavy regulation on the platform economy, these days some
jurisdictions take a more interventionist approach to stem the tide of digitalization which appears to thrive in legal vacuum giving rise to unequal competition. The findings suggest that platforms exert
much influence on the employment structures, giving rise to cohorts of precariat and gig workers,
resulting in unequal distribution of wealth. In this work the author concentrates on the revolutionary
impact of sharing platforms on society, labour market and its structure, as well as legal norms that
call for comprehensive revision in order to maintain welfare in the changing environment. As this
paper remains fairly conceptual, the author attempts at an indication of major trends which are likely
to emerge in society, and a contest of the idea of unharnessed development of sharing platforms.Tworzenie i wykorzystanie platform cyfrowych wykazuje tendencję wzrostową nie tylko
w sektorze prywatnym, ale także publicznym. W literaturze przedmiotu można napotkać ożywioną
dyskusję dotyczącą wpływu cyfryzacji na zatrudnienie, struktury społeczne, zarządzanie sektorem
publicznym, a także na inicjatywy przedsiębiorcze i biznes. Chociaż niektóre wczesne przeglądy
sprzeciwiły się narzuceniu surowych regulacji dla gospodarki platformowej, obecnie niektóre jurysdykcje
przyjmują bardziej interwencjonistyczne podejście, chcąc powstrzymać falę cyfryzacji, która
wydaje się kwitnąć w próżni prawnej, wywołując nieuczciwą konkurencję. Dotychczasowe badania
sugerują, że platformy wywierają duży wpływ na strukturę zatrudnienia, co powoduje powstawanie
rzesz pracowników tymczasowych tworzących prekariat, czego konsekwencją jest nierówny podział
bogactwa w społeczeństwie. W niniejszym opracowaniu autor koncentruje się na rewolucyjnym
wpływie cyfrowych platform na społeczeństwo, rynek pracy i jego strukturę, a także porusza
tematykę unormowań prawnych, które wymagają kompleksowej rewizji w celu utrzymania dobrobytu
w zmieniającym się otoczeniu. Niniejszy artykuł ma charakter koncepcyjny – autor próbuje
wskazać główne trendy, które prawdopodobnie pojawią się w społeczeństwie jako efekt rewolucji
informacyjnej i towarzyszącemu jej rozwojowi przemysłu 4.0 oraz kwestionuje ideę nieograniczonego
rozwoju ekonomii współdzielenia opartej o platformy cyfrowe
Dobre praktyki edukacji wielokulturowej na przykładzie Społecznego Gimnazjum nr 20 „Raszyńska” w Warszawie
Get PDFThis article is an attempt to present the good practices of intercultural education. By the introducing into the main problems, the author presents the education rules of foreigners in the Polish education system, indicating the most important aspects of Polish law regulations. Then defines the one of the most important concepts of intercultural education and multicultural education, discussing its main goals and tasks. The crucial question raised in the text is the role of the school in the intercultural education and shaping of intercultural competence in education among pupils by the teacher. At this point, the author attempts to answer the question whether and how Polish schools and teachers are prepared to accept foreign children? And what is the role of the teacher in intercultural education? In the second part of the text, they presented good practices of intercultural education as an example the Social Secondary School No. 20 “Raszyńska” in Warsaw
MESON PHYSICS AT HERA
No full text The recent, selected results on meson production at HERA electron-proton collider from the H1 and ZEUS experiments are presented and interpreted within the framework of quantum chromodynamics. </jats:p
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