Neutrino Mass and Oscillation

The question of neutrino mass is one of the major riddles in particle physics. Recently, strong evidence that neutrinos have nonzero masses has been found. While tiny, these masses could be large enough to contribute significantly to the mass density of the universe. The evidence for nonvanishing neutrino masses is based on the apparent observation of neutrino oscillation -- the transformation of a neutrino of one type or "flavor" into one of another. We explain the physics of neutrino oscillation, and review and weigh the evidence that it actually occurs in nature. We also discuss the constraints on neutrino mass from cosmology and from experiments with negative results. After presenting illustrative neutrino mass spectra suggested by the present data, we consider how near- and far-future experiments can further illuminate the nature of neutrinos and their masses.Comment: 43 pages, 8 figures, to appear in the Annual Review of Nuclear and Particle Science, Vol. 49 (1999

MiniBooNE and LSND data: non-standard neutrino interactions in a (3+1) scheme versus (3+2) oscillations

The recently observed event excess in MiniBooNE anti-neutrino data is in agreement with the LSND evidence for electron anti-neutrino appearance. We propose an explanation of these data in terms of a (3+1) scheme with a sterile neutrino including non-standard neutrino interactions (NSI) at neutrino production and detection. The interference between oscillations and NSI provides a source for CP violation which we use to reconcile different results from neutrino and anti-neutrino data. Our best fit results imply NSI at the level of a few percent relative to the standard weak interaction, in agreement with current bounds. We compare the quality of the NSI fit to the one obtained within the (3+1) and (3+2) pure oscillation frameworks. We also briefly comment on using NSI (in an effective two-flavour framework) to address a possible difference in neutrino and anti-neutrino results from the MINOS experiment.Comment: 28 pages, 9 figures, discussion improved, new appendix added, conclusions unchange

Low-Energy Probes of a Warped Extra Dimension

We investigate a natural realization of a light Abelian hidden sector in an extended Randall-Sundrum (RS) model. In addition to the usual RS bulk we consider a second warped space containing a bulk U(1)_x gauge theory with a characteristic IR scale of order a GeV. This Abelian hidden sector can couple to the standard model via gauge kinetic mixing on a common UV brane. We show that if such a coupling induces significant mixing between the lightest U(1)_x gauge mode and the standard model photon and Z, it can also induce significant mixing with the heavier U(1)_x Kaluza-Klein (KK) modes. As a result it might be possible to probe several KK modes in upcoming fixed-target experiments and meson factories, thereby offering a new way to investigate the structure of an extra spacetime dimension.Comment: 26 pages, 1 figure, added references, corrected minor typos, same as journal versio

A Mathematical model for Astrocytes mediated LTP at Single Hippocampal Synapses

Many contemporary studies have shown that astrocytes play a significant role in modulating both short and long form of synaptic plasticity. There are very few experimental models which elucidate the role of astrocyte over Long-term Potentiation (LTP). Recently, Perea & Araque (2007) demonstrated a role of astrocytes in induction of LTP at single hippocampal synapses. They suggested a purely pre-synaptic basis for induction of this N-methyl-D- Aspartate (NMDA) Receptor-independent LTP. Also, the mechanisms underlying this pre-synaptic induction were not investigated. Here, in this article, we propose a mathematical model for astrocyte modulated LTP which successfully emulates the experimental findings of Perea & Araque (2007). Our study suggests the role of retrograde messengers, possibly Nitric Oxide (NO), for this pre-synaptically modulated LTP.Comment: 51 pages, 15 figures, Journal of Computational Neuroscience (to appear

High frequency of CHD7 mutations in congenital hypogonadotropic hypogonadism

Congenital hypogonadotropic hypogonadism (CHH) is characterized by lack of normal pubertal development due to deficient gonadotropin-releasing hormone (GnRH) secretion or action, and is caused by genetic defects in several genes. Mutations in the CHD7 gene cause CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and development, Genital hypoplasia and Ear abnormalities), but have also been found in patients with isolated CHH. The aim of this study was to identify CHD7 mutations in patients with CHH. Fifty Portuguese patients with CHH were screened for mutations in the CHD7 gene by DNA sequencing. Eight (16%) patients had CHD7 rare sequence variants that consisted of six missense (p.Gly388Glu, p.His903Pro, p.Thr1082Ile, p.Val1452Leu, p.Asp1854Gly, and p.Arg2065His) and two synonymous (p.Ser559Ser, and p.Ala2785Ala) mutations. Five of these mutations have never been reported before. Three CHD7 mutations occurred in patients that had mutations in additional CHH-genes. This study uncovered novel genetic variants that expand the known spectrum of mutations associated with CHH. The frequency of CHD7 mutations in this cohort was higher than that of other major CHH-genes and confirms the importance of including CHD7 in the genetic testing of CHH, even in the absence of additional CHARGE features.info:eu-repo/semantics/publishedVersio

The EpsE Flagellar Clutch Is Bifunctional and Synergizes with EPS Biosynthesis to Promote Bacillus subtilis Biofilm Formation

Many bacteria inhibit motility concomitant with the synthesis of an extracellular polysaccharide matrix and the formation of biofilm aggregates. In Bacillus subtilis biofilms, motility is inhibited by EpsE, which acts as a clutch on the flagella rotor to inhibit motility, and which is encoded within the 15 gene eps operon required for EPS production. EpsE shows sequence similarity to the glycosyltransferase family of enzymes, and we demonstrate that the conserved active site motif is required for EPS biosynthesis. We also screen for residues specifically required for either clutch or enzymatic activity and demonstrate that the two functions are genetically separable. Finally, we show that, whereas EPS synthesis activity is dominant for biofilm formation, both functions of EpsE synergize to stabilize cell aggregates and relieve selective pressure to abolish motility by genetic mutation. Thus, the transition from motility to biofilm formation may be governed by a single bifunctional enzyme

Oncolytic adenovirus co-expressing IL-12 and IL-18 improves tumor-specific immunity via differentiation of T cells expressing IL-12Rβ2 or IL-18Rα

The oncolytic adenovirus (Ad) is currently being advanced as a promising antitumor remedy as it selectively replicates in tumor cells and can transfer and amplify therapeutic genes. Interleukin (IL)-12 induces a potent antitumor effect by promoting natural killer (NK) cell and cytotoxic T cell activities. IL-18 also augments cytotoxicity of NK cells and proliferation of T cells. This effect further enhances the function of IL-12 in a synergistic manner. Therefore, we investigated for the first time an effective cancer immunogene therapy of syngeneic tumors via intratumoral administration of oncolytic Ad co-expressing IL-12 and IL-18, RdB/IL-12/IL-18. Intratumoral administration of RdB/IL-12/IL-18 improved antitumor effects, as well as increased survival, in B16-F10 murine melanoma model. The ratio of T-helper type 1/2 cytokine as well as the levels of IL-12, IL-18, interferon-γ and granulocyte–macrophage colony-stimulating factor was markedly elevated in RdB/IL-12/IL-18-treated tumors. Mice injected with RdB/IL-12/IL-18 also showed enhanced cytotoxicity of tumor-specific immune cells. Consistent with these results, immense necrosis and infiltration of NK cells, as well as CD4+ and CD8+ T cells, were observed in RdB/IL-12/IL-18-treated tumor tissues. Importantly, tumors treated with RdB/IL-12/IL-18 showed an elevated number of T cells expressing IL-12Rβ2 or IL-18Rα. These results provide a new insight into therapeutic mechanisms of IL-12 plus IL-18 and provide a potential clinical cancer immunotherapeutic agent for improved antitumor immunity

Cardiac T1 Mapping and Extracellular Volume (ECV) in clinical practice: a comprehensive review.

Cardiovascular Magnetic Resonance is increasingly used to differentiate the aetiology of cardiomyopathies. Late Gadolinium Enhancement (LGE) is the reference standard for non-invasive imaging of myocardial scar and focal fibrosis and is valuable in the differential diagnosis of ischaemic versus non-ischaemic cardiomyopathy. Diffuse fibrosis may go undetected on LGE imaging. Tissue characterisation with parametric mapping methods has the potential to detect and quantify both focal and diffuse alterations in myocardial structure not assessable by LGE. Native and post-contrast T1 mapping in particular has shown promise as a novel biomarker to support diagnostic, therapeutic and prognostic decision making in ischaemic and non-ischaemic cardiomyopathies as well as in patients with acute chest pain syndromes. Furthermore, changes in the myocardium over time may be assessed longitudinally with this non-invasive tissue characterisation method

The Cultural Transmission of Prestige and Dominance Social Rank Cues: an Experimental Simulation

This is the final version. Available from Springer via the DOI in this record.Below is the link to the dataset and preview of the experiment, and Dataset (CSV, 133KB) - process_raw_data_included.csv can be found in the Electronic Supplementary Material section Preview of the experiment: https://exetercles.eu.qualtrics.com/jfe/form/SV_071cfHiCY9qBEkB.Informal social hierarchies within small human groups are argued to be based on prestige, dominance, or a combination of the two (Henrich & Gil-White, 2001). Prestige-based hierarchies entail the ordering of individuals by the admiration and respect they receive from others due to their competence within valued domains. This type of hierarchy provides benefits for subordinates such as social learning opportunities and both private and public goods. In contrast, dominance-based hierarchies entail the ordering of individuals by their capacity to win fights, and coerce or intimidate others. This type of hierarchy produces costs in subordinates due to its aggressive and intimidating nature. Given the benefits and costs associated with these types of social hierarchies for subordinates, we hypothesised that prestige and dominance cues are better recalled and transmitted than social rank cues that do not elicit high prestige or dominance associations (i.e. medium social rank cues). Assuming that for the majority of the population who are not already at the top of the social hierarchy it is more important to avoid the costs of dominance-based hierarchies than to obtain the benefits of prestige-based hierarchies, we further hypothesised that dominance cues are better transmitted than prestige cues. We conducted a recall-based transmission chain experiment with 30 chains of four generations each (N = 120). Participants read and recalled descriptions of prestigious, dominant, and medium social rank footballers, and their recall was passed to the next participant within their chain. As predicted, we found that both prestige cues and dominance cues were better transmitted than medium social rank cues. However, we did not find support for our prediction of the better transmission of dominance cues than prestige cues. We discuss whether the results might be explained by a specific social-rank content transmission bias or by a more general emotional content transmission bias.University of Exete