A mathematical and computational review of Hartree-Fock SCF methods in Quantum Chemistry

We present here a review of the fundamental topics of Hartree-Fock theory in Quantum Chemistry. From the molecular Hamiltonian, using and discussing the Born-Oppenheimer approximation, we arrive to the Hartree and Hartree-Fock equations for the electronic problem. Special emphasis is placed in the most relevant mathematical aspects of the theoretical derivation of the final equations, as well as in the results regarding the existence and uniqueness of their solutions. All Hartree-Fock versions with different spin restrictions are systematically extracted from the general case, thus providing a unifying framework. Then, the discretization of the one-electron orbitals space is reviewed and the Roothaan-Hall formalism introduced. This leads to a exposition of the basic underlying concepts related to the construction and selection of Gaussian basis sets, focusing in algorithmic efficiency issues. Finally, we close the review with a section in which the most relevant modern developments (specially those related to the design of linear-scaling methods) are commented and linked to the issues discussed. The whole work is intentionally introductory and rather self-contained, so that it may be useful for non experts that aim to use quantum chemical methods in interdisciplinary applications. Moreover, much material that is found scattered in the literature has been put together here to facilitate comprehension and to serve as a handy reference.Comment: 64 pages, 3 figures, tMPH2e.cls style file, doublesp, mathbbol and subeqn package

Temporal and Individual Variation in Offspring Provisioning by Tree Swallows: A New Method of Automated Nest Attendance Monitoring

Studies of the ecology and evolution of avian nesting behavior have been limited by the difficulty and expense of sampling nest attendance behavior across entire days or throughout a substantial portion of the nestling period. Direct observation of nesting birds using human observers and most automated devices requires sub-sampling of the nestling period, which does not allow for the quantification of the duration of chick-feeding by parents within a day, and may also inadequately capture temporal variation in the rate at which chicks are fed. Here I describe an inexpensive device, the Automated Perch Recorder (APR) system, which collects accurate, long-term data on hourly rates of nest visitation, the duration of a pair's workday, and the total number of visits the pair makes to their nest across the entire period for which it is deployed. I also describe methods for verifying the accuracy of the system in the field, and several examples of how these data can be used to explore the causes of variation in and tradeoffs between the rate at which birds feed their chicks and the total length of time birds spend feeding chicks in a day

Mapping the meaning of "difference' in Europe: A social topography of prejudice

This paper draws on original empirical research to investigate popular understandings of prejudice in two national contexts: Poland and the United Kingdom. The paper demonstrates how common-sense meanings of prejudice are inflected by the specific histories and geographies of each place: framed in terms of ‘distance’ (Poland) and ‘proximity’ (United Kingdom), respectively. Yet, by treating these national contexts as nodes and linking them analytically the paper also exposes a connectedness in these definitions which brings into relief the common processes that produce prejudice. The paper then explores how inter-linkages between the United Kingdom and Poland within the wider context of the European Union are producing – and circulating through the emerging international currency of ‘political correctness’ – a common critique of equality legislation and a belief that popular concerns about the way national contexts are perceived to be changing as a consequence of super mobility and super diversity are being silenced. This raises a real risk that in the context of European austerity and associated levels of socioeconomic insecurity, negative attitudes and conservative values may begin to be represented as popular normative standards which transcend national contexts to justify harsher political responses towards minorities. As such, the paper concludes by making a case for prejudice reduction strategies to receive much greater priority in both national and European contexts

Setting an Optimal α That Minimizes Errors in Null Hypothesis Significance Tests

Null hypothesis significance testing has been under attack in recent years, partly owing to the arbitrary nature of setting α (the decision-making threshold and probability of Type I error) at a constant value, usually 0.05. If the goal of null hypothesis testing is to present conclusions in which we have the highest possible confidence, then the only logical decision-making threshold is the value that minimizes the probability (or occasionally, cost) of making errors. Setting α to minimize the combination of Type I and Type II error at a critical effect size can easily be accomplished for traditional statistical tests by calculating the α associated with the minimum average of α and β at the critical effect size. This technique also has the flexibility to incorporate prior probabilities of null and alternate hypotheses and/or relative costs of Type I and Type II errors, if known. Using an optimal α results in stronger scientific inferences because it estimates and minimizes both Type I errors and relevant Type II errors for a test. It also results in greater transparency concerning assumptions about relevant effect size(s) and the relative costs of Type I and II errors. By contrast, the use of α = 0.05 results in arbitrary decisions about what effect sizes will likely be considered significant, if real, and results in arbitrary amounts of Type II error for meaningful potential effect sizes. We cannot identify a rationale for continuing to arbitrarily use α = 0.05 for null hypothesis significance tests in any field, when it is possible to determine an optimal α

At work and play; business events as entrepreneurial spaces

There is inadequate literature examining, and illustrating, the integration of play and business events and how this facilitates entrepreneurial opportunities. Business events are distinct from the patterns of ordinary life and increasingly offer participants an ‘invitation to play’, encouraging socialization and trust. This article examines the role of play in the design of business events and how this can enable entrepreneurial outcomes. Through examination of diverse, but related, literature and three contrasting, empirically based, case studies, this article illustrates how event creators take an increasingly entrepreneurial approach. These cases range from a charity event with participants sleeping with the homeless on a city’s streets, a major flooring manufacturer designing events to outsource innovation and an imaginative event activity termed ‘coffee and papers’. Designing events that fuse, rather than polarize, play and work enables business event settings, and activities, which trigger entrepreneurial outcomes. This article adds to the embryonic literature and concludes by identifying four principles that underlie the effectual facilitation of play in a business event setting

Human neutrophil clearance of bacterial pathogens triggers anti-microbial gamma delta T cell responses in early infection

Human blood Vc9/Vd2 T cells, monocytes and neutrophils share a responsiveness toward inflammatory chemokines and are rapidly recruited to sites of infection. Studying their interaction in vitro and relating these findings to in vivo observations in patients may therefore provide crucial insight into inflammatory events. Our present data demonstrate that Vc9/Vd2 T cells provide potent survival signals resulting in neutrophil activation and the release of the neutrophil chemoattractant CXCL8 (IL-8). In turn, Vc9/Vd2 T cells readily respond to neutrophils harboring phagocytosed bacteria, as evidenced by expression of CD69, interferon (IFN)-c and tumor necrosis factor (TNF)-a. This response is dependent on the ability of these bacteria to produce the microbial metabolite (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP), requires cell-cell contact of Vc9/Vd2 T cells with accessory monocytes through lymphocyte function-associated antigen-1 (LFA-1), and results in a TNF-a dependent proliferation of Vc9/Vd2 T cells. The antibiotic fosmidomycin, which targets the HMB-PP biosynthesis pathway, not only has a direct antibacterial effect on most HMB-PP producing bacteria but also possesses rapid anti-inflammatory properties by inhibiting cd T cell responses in vitro. Patients with acute peritoneal-dialysis (PD)-associated bacterial peritonitis – characterized by an excessive influx of neutrophils and monocytes into the peritoneal cavity – show a selective activation of local Vc9/Vd2 T cells by HMB-PP producing but not by HMB-PP deficient bacterial pathogens. The cd T celldriven perpetuation of inflammatory responses during acute peritonitis is associated with elevated peritoneal levels of cd T cells and TNF-a and detrimental clinical outcomes in infections caused by HMB-PP positive microorganisms. Taken together, our findings indicate a direct link between invading pathogens, neutrophils, monocytes and microbe-responsive cd T cells in early infection and suggest novel diagnostic and therapeutic approaches.Martin S. Davey, Chan-Yu Lin, Gareth W. Roberts, Sinéad Heuston, Amanda C. Brown, James A. Chess, Mark A. Toleman, Cormac G.M. Gahan, Colin Hill, Tanya Parish, John D. Williams, Simon J. Davies, David W. Johnson, Nicholas Topley, Bernhard Moser and Matthias Eber

Prolactin signaling and Stat5: going their own separate ways?

Miyoshi et al. compared the role of the prolactin receptor (PrlR) and its downstream mediator, the signal transducer and activator of transcription 5 (Stat5), in mammary epithelial cells in vivo by studying PrlR(-/-) and Stat5ab(-/-) mouse mammary epithelial transplants during pregnancy. At first glance, the two mutant epithelia appear to have similar defects in the differentiation of the alveolar epithelium. However, a closer examination by Miyoshi et al. revealed defects in the epithelial architecture of the smallest ducts of Stat5ab(-/-) transplants not apparent in the PrlR(-/-) transplants, suggesting that Stat5 is more than a simple mediator of PrlR action

Children’s discourses of natural spaces: considerations for children’s subjective well-being

Based on the evidence provided in the literature, it is manifest that increased time spent in nature increases various aspects of children’s well-being. Using discourse analysis on focus group interviews with 28 children between the ages of 12 and 14 years old from three socio-economically diverse communities in the Western Cape of South Africa, the study aimed to explore how children construct and assign meaning to natural spaces. More specifically the study explored how children use specific discursive resources and repertoires to construct and assign meaning to their engagement with natural spaces, and the extent to which this influences their subjective well-being. Several pertinent discourses emerged from the participants’ accounts within four themes of: Safety and natural spaces, Appreciation for natural spaces, Degradation of Nature: Thinking environmentally, acting pro-environmentally, and Natural spaces and children’s subjective well-being. The study highlights the critical role that children’s engagement in natural spaces has on their subjective well-being, and how these benefits can be harnessed to better children’s overall quality of life.IS