Bounds on Dark Matter Interactions with Electroweak Gauge Bosons

We investigate scenarios in which dark matter interacts with the Standard Model primarily through electroweak gauge bosons. We employ an effective field theory framework wherein the Standard Model and the dark matter particle are the only light states in order to derive model-independent bounds. Bounds on such interactions are derived from dark matter production by weak boson fusion at the LHC, indirect detection searches for the products of dark matter annihilation and from the measured invisible width of the $Z^0$. We find that limits on the UV scale, $\Lambda$, reach weak scale values for most operators and values of the dark matter mass, thus probing the most natural scenarios in the WIMP dark matter paradigm. Our bounds suggest that light dark matter (m_{\chi}\lsim m_Z/2 or m_{\chi}\lsim 100-200\gev, depending on the operator) cannot interact only with the electroweak gauge bosons of the Standard Model, but rather requires additional operator contributions or dark sector structure to avoid overclosing the universe.Comment: 45 pages, 26 figure

X-ray response of tunnel junctions with a trapping layer

The use of trapping layers in superconductive tunnel junctions may drastically improve their functioning as X-ray detectors. Information about these trapping layers can be obtained from I/V-curves and X-ray spectra. The application of a magnetic field causes a substantial reduction of the bandgap in the trapping layer

Transfer-Matrix Monte Carlo Estimates of Critical Points in the Simple Cubic Ising, Planar and Heisenberg Models

The principle and the efficiency of the Monte Carlo transfer-matrix algorithm are discussed. Enhancements of this algorithm are illustrated by applications to several phase transitions in lattice spin models. We demonstrate how the statistical noise can be reduced considerably by a similarity transformation of the transfer matrix using a variational estimate of its leading eigenvector, in analogy with a common practice in various quantum Monte Carlo techniques. Here we take the two-dimensional coupled $XY$-Ising model as an example. Furthermore, we calculate interface free energies of finite three-dimensional O($n$) models, for the three cases $n=1$, 2 and 3. Application of finite-size scaling to the numerical results yields estimates of the critical points of these three models. The statistical precision of the estimates is satisfactory for the modest amount of computer time spent

Possible Indication of Narrow Baryonic Resonances Produced in the 1720-1790 MeV Mass Region

Signals of two narrow structures at M=1747 MeV and 1772 MeV were observed in the invariant masses M_{pX} and M_{\pi^{+}X} of the pp->ppX and pp->p\pi^{+}X reactions respectively. Many tests were made to see if these structures could have been produced by experimental artefacts. Their small widths and the stability of the extracted masses lead us to conclude that these structures are genuine and may correspond to new exotic baryons. Several attempts to identify them, including the possible "missing baryons" approach, are discussed.Comment: 17 pages including 8 figures and 3 tables. ReVte

L’Histoire de la peinture en Italie : un sanctuaire pour l’heureux petit nombre

In the Histoire de la peinture en Italie (1817), Stendhal does not describe the paintings. He depreciates the formal aspect of the art of painting because he assigns to it a symbolic fonction : painting is constructed spirituality. To speak about painting is to educate the reader’s sensibility in order for him to create a bond of sympathy with the soul of the artist  and of his figures. Painting becomes a sanctuary. To keep away the non believers, Stendhal elaborates a encrypted writing intended for the happy few

Pea proteins for piglets : effects on digestive processes

White-flowered pea ( Pisum sativum ) contains 20 to 25% crude protein (Nx6.25). The pea proteins consist in globulins (60%) and albumins (25%). Because the pea albumin proteins have biological activities due to their metabolic roles in the seed, some of them are called antinutritional factors (ANFs) for monogastric animals. These are mainly protease inhibitors and lectins. The apparent ileal digestibility of N and amino acids of raw peas fed to piglets was low. The N apparent ileal digestibility of pea protein isolate consisting mainly of globulins without ANFs was 15 units higher. The addition of 3% of pea ANF concentrate decreased the N apparent ileal digestibility by 7 units. This effect is not entirely due to the alleged antinutritional activities of die protease inhibitors or the lectins. This was suggested by the results of the incorporation of another pea ANF concentrate with a higher ANF content than the former concentrate. The albumin proteins themselves were suspected to be low digestible. This was illustrated by the results of a mathematical study of the amino acid composition of ileal digesta from piglets fed a raw pea diet, showing that these amino acids would be mainly of "endogenous + bacterial" origin and partly of dietary origin and especially of albumin type. No relations, neither between N digestibility and pancreatic protease activity in the pancreatic tissue, in its secretions or in the small intestinal digesta, neither between the activities in these different sections of the gastro-intestinal tract could be established. The trypsin and chymotrypsin activity decreased in the jejunal digesta and increased in the ileo-caecal digesta upon addition of pea ANF concentrate to a pea protein isolate diet although the N apparent ileal digestibility was not affected. The enzyme activities in the pancreatic tissue was decreased with a raw pea diet compared to a pea protein isolate diet although equivalent activities were found in the pancreatic secretions. These observations suggested that the mode of action of pea protease inhibitors may depend on the demand of proteases to hydrolyse the dietary proteins in the upper intestine, and on the nutritional quality of the dietary proteins associated with these protease inhibitors

1H NMR determination of the self-association of an acridine homodimer and its complexation with ethidium bromide in aqueous solution

1H NMR spectroscopy (500MHz) has been used to investigate the self-association in aqueous buffered solution of a bis-intercalator, Acridine Homodimer (AcrH), and its hetero-association with the aromatic dye, Ethidium Bromide (EB). The equilibrium constants and thermodynamical parameters (enthalpy and entropy) of self-association have been determined from the observed concentration and temperature dependences of chemical shifts of AcrH protons and the results are consistent with a model consisting of at least four distinct forms of AcrH molecules in solution: unfolded (U), folded (F), a dimer formed from two folded molecules (F2) and a trimer formed from three folded molecules (F3). It has also been shown that Ethidium Bromide complexes strongly to the dimer form (F2) of the bis-acridine molecule, AcrH. Comparison of the calculated association parameters of AcrH with the previously studied Ethidium Homodimer (EBH) revealed a correlation between the effectiveness of complexation and the length of chain connecting the chromophores of a bis-intercalator

Ubuntu and values underlying the Vatsonga culture : implications for developmental social work with children

The article is based on a doctoral study submitted at the University of Pretoria.The development of the social work profession in Western countries is criticised as being irrelevant to the African context. Although developmental social work was introduced in South Africa to align the profession with African contexts and adopted in some southern African countries, the acknowledgement of African indigenous knowledge systems remains a neglected area. In this article, we present the findings of the study that explored the use of Vatsonga indigenous knowledge in child protection. By using a qualitative study as the basis, the researcher conducted semi-structured interviews with 40 Vatsonga elders who were keepers of their indigenous knowledge. The research findings indicate that beliefs and practices based on the African principles underlying ubuntu have a strong focus on enhancing the well-being of children, including orphans and vulnerable children, and could relate to the central goal and the concepts underlying developmental social work. We conclude that there is a strong association between the principles of ubuntu and developmental social work interventions that focus on the well-being of children.A Postgraduate Research Support Scholarship of the University of Pretoria.https://unisapressjournals.co.za/index.php/SWPR/indexam2023Social Work and Criminolog

Exposure to substance use in the social environment : the experiences of adolescents in the Tshwane Metropole

The premise of this study is that if exposure to substance use in the social environment of adolescents is understood, macro interventions could be recommended to promote adolescents’ right to live in a safe and sustainable environment. The aim of the study was to explore adolescents’ experiences of exposure to substance use in their social environment, other than the home. A qualitative research approach was adopted and 40 semi-structured interviews were conducted. Adolescent participants, of both genders between 11 and 18 years, were recruited across the Tshwane Metropole. The Social Learning Theory underpinned this study as it offers concepts and principles for understanding how social environmental factors impact on adolescents’ behaviour. Key findings indicated that exposure to substance use is highly prevalent amongst adolescents in the Tshwane Metropole and could be normalised in their social reality. Recommendations are offered for appropriate macro interventions in line with a developmental approach.http://www.uj.ac.za/EN/Faculties/humanities/departments/socialwork/TheSocialWorkPractionerResearcherJournal/Pages/home.aspxam2016Social Work and Criminolog