37 research outputs found
Citizenship and state succession in the Sudans
No full textBronwen Manby is senior programme adviser on Africa with the Open Society Foundations, and author of two books on nationality law in Africa. She is an expert adviser on citizenship for UNHCR’s Khartoum office and wrote an article on citizenship issues and the options for resolving them in advance of the secession of South Sudan. She is currently on sabbatical leave, based in the Centre for Human Rights at LSE. This post also appears on the Open Society Foundations blog
Calculation of properties of crystalline lithium hydride using correlated wave function theory
No full textThe lattice parameter, bulk modulus, and cohesive energy of lithium hydride are calculated to very high accuracy through a combination of periodic and finite-cluster electronic structure calculations. The Hartree-Fock contributions are taken from earlier work in which plane-wave calculations were corrected for pseudo-potential errors. Molecular electronic structure calculations on finite clusters are then used to compute the correlation contributions and finite-size effects are removed through the hierarchical scheme. The systematic improvability of the molecular electronic structure methods makes it possible to converge the static cohesive energy to within a few tenths of a millihartree. Zero-point energy contributions are determined from density functional theory phonon frequencies. All calculated properties of lithium hydride and deuteride agree with empirical observations to within experimental uncertainty
Preventing statelessness among migrants and refugees: birth registration and consular assistance in Egypt and Morocco
No full textThis paper presents a synthesis of research findings on the identification needs of Sub-Saharan African and other migrants and refugees in Egypt and Morocco, particularly focusing on children born outside the country of nationality of their parents. The paper sets out the legislative and regulatory frameworks in place for birth registration and issue of identity documents, and reports the findings of focus groups and interviews with migrants and refugees on the implementation of these frameworks in practice, highlighting obstacles to the registration of the births of children of foreign parents and the difficulties of obtaining documents from the consular authorities of the country of origin. The paper provides recommendations for legal and administrative reform in Egypt and Morocco, to ensure that both children and adults can have access to documents that officially confirm their nationality. The research is set within the context of international policy objectives and discussions on the provision of ‘legal identity to all’, highlighting the dangers of exclusion and statelessness if the obstacles identified by the report are not addressed. About the Author Bronwen Manby is Senior Policy Fellow at the LSE Middle East Centre and Principal Investigator for the research project ‘Preventing Statelessness among Migrants in North Africa’. She has written extensively on nationality and statelessness in Africa
Local explicitly correlated second-order perturbation theory for the accurate treatment of large molecules
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The history and antiquities of the Parish of Saint David, South-Wales, the most ancient documents collected from the Bodleian library To which is annexed, a Correct List of the Archbishops, Bishops, &c. who have filled that Sée ; Embellished with plates in aquatinta, from Drawings made on the Spot, by the Author
No full textEvaluating physical activity
No full textPhysical activity as a public health intervention is still a relatively
new concept and although the health benefits of activity are widely
acknowledged (1) there is still no consensus as to the most effective
way of getting people to become more active. This has led to calls
for ‘properly designed’ evaluation studies (2) and has elevated
the importance of finding out what works. This article examines
evaluation methods and looks at the dilemmas and some of the
successful approaches experienced by the author
Ab initio calculations on properties of low-lying electronic states of the SiF3. radical
No full textA recent vacuum-UV fluorescence spectrum of SiF (Biehl et al. J. Chem. Phys., 107 (1997) 720) has yielded information about the decay of electronically excited states of neutral fragments and the parent molecular cation. Emission in the visible region > 380 nm) has been observed for an excitation energy of 13.0 eV with a lifetime of 3.9 ns, but the emitter was not assigned. Ab initio CASSCF calculations show that the observed emission is due to the A A - X A transition in the SiF radical. The experimental lifetime, however, is too short to be attributed to this radiative process. We suggest that the lifetime is dominated by rapid internal conversion of SiF A A into high vibrational levels of the ground state
Tensor factorizations of local second-order Mller-Plesset theory
No full textEfficient electronic structure methods can be built around efficient tensor representations of the wavefunction. Here we first describe a general view of tensor factorization for the compact representation of electronic wavefunctions. Next, we use this language to construct a low-complexity representation of the doubles amplitudes in local second-order Mller-Plesset perturbation theory. We introduce two approximations-the direct orbital-specific virtual approximation and the full orbital-specific virtual approximation. In these approximations, each occupied orbital is associated with a small set of correlating virtual orbitals. Conceptually, the representation lies between the projected atomic orbital representation in Pulay-Saeb local correlation theories and pair natural orbital correlation theories. We have tested the orbital-specific virtual approximations on a variety of systems and properties including total energies, reaction energies, and potential energy curves. Compared to the Pulay-Saeb ansatz, we find that these approximations exhibit favorable accuracy and computational times while yielding smooth potential energy curves.published_or_final_versio
