Consistent supersymmetric Kaluza--Klein truncations with massive modes

We construct consistent Kaluza--Klein reductions of D=11 supergravity to four dimensions using an arbitrary seven-dimensional Sasaki--Einstein manifold. At the level of bosonic fields, we extend the known reduction, which leads to minimal N=2 gauged supergravity, to also include a multiplet of massive fields, containing the breathing mode of the Sasaki--Einstein space, and still consistent with N=2 supersymmetry. In the context of flux compactifications, the Sasaki--Einstein reductions are generalizations of type IIA SU(3)-structure reductions which include both metric and form-field flux and lead to a massive universal tensor multiplet. We carry out a similar analysis for an arbitrary weak G_2 manifold leading to an N=1 supergravity with massive fields. The straightforward extension of our results to the case of the seven-sphere would imply that there is a four-dimensional Lagrangian with N=8 supersymmetry containing both massless and massive spin two fields. We use our results to construct solutions of M-theory with non-relativistic conformal symmetry.Comment: 33 pages. v2: Added section on skew-whiffed solutions and some brief comments on holographic superconductors. v3: typos corrected, version to be published in JHE

Excitation wavelength dependent pump–probe signatures of molecular crystals

The photodynamics of single crystals of 4-(diisopropylamino)benzonitrile (DIABN) have been studied by femtosecond UV/Vis and mid-IR absorption spectroscopy. The observed spectroscopic response, especially in the UV/Vis, strongly depends on the optical excitation conditions. For the excitation light in resonance with the absorption of DIABN, broad and structureless transient spectra are observed, which decay non-exponentially within pico- to nanoseconds. For off-resonance excitation in the very red wing of the absorption band a stimulated emission signal is detected, which decays in ~10 ps matching the known behavior of the non-interacting chromophore in solution. The 10 ps decay is due to an intramolecular charge transfer process which is supported by femtosecond IR spectroscopy. The observed dependence on the excitation wavelength is assigned to a change in the density of excited chromophores and therefore bears relevance for time resolved X-ray diffraction experiments.

Photochromic Bis(thiophen-3-yl)maleimides Studied with Time-Resolved Spectroscopy

The dynamics of the ring-closure reaction of three different bis(thiophen-3-yl)maleimides are investigated using ultrafast spectroscopy in the visible range. The structures of the molecules differ with respect to substitution of the thiophene ring and the maleimide. The experiments reveal reaction kinetics which point to the population of an excited electronic state for several nanoseconds. In the case of completely unsubstituted thiophene rings, a long excited-state lifetime (biexponential decay with 3 and 15 ns) can be observed. The remaining ultrafast absorption transients of this molecule are due to relaxational processes on the excited electronic potential energy surface. The ring-closure reaction has a small yield (<1%) and does not show up in the ultrafast absorption experiments. A dimethyl substitution of the thiophene ring results in completely different behavior: after transients related to relaxation in the excited electronic state, one finds pronounced absorption transients with τ = 16 ps which represent the partial decay of the excited electronic state and the formation of the ring-closed isomer. Another fraction of the emitting excited electronic state decays again on the few nanosecond time scale. The experiments suggest that the open isomer of the dimethyl-substituted imides exists in two conformations.

Supplementary Material for: Candida albicans and Early Childhood Caries: A Systematic Review and Meta-Analysis

<p>Oral <i>Candida albicans</i> has been detected in children with early childhood caries (ECC) and has demonstrated cariogenic traits in animal models of the disease. Conversely, other studies found no positive correlation between <i>C. albicans</i> and caries experience in children, while suggesting it may have protective effects as a commensal organism. Thus, this study aimed to examine whether oral <i>C. albicans</i> is associated with ECC. Seven electronic databases were searched. The data from eligible studies were extracted, and the risk of bias was evaluated. A fixed effects model (Mantel-Haenszel estimate) was used for meta-analysis, and the summary effect measure was calculated by odds ratio (OR) and 95% confidence interval (CI). Fifteen cross-sectional studies were included for the qualitative assessment and 9 studies for meta-analysis. Twelve studies revealed higher oral <i>C. albicans</i> prevalence in ECC children than in caries-free children, while 2 studies indicated an equivalent prevalence. A pooled estimate, with OR = 6.51 and 95% CI = 4.94-8.57, indicated a significantly higher ECC experience in children with oral <i>C. albicans</i> than those without <i>C. albicans</i> (<i>p</i> < 0.01). The odds of experiencing ECC in children with <i>C. albicans</i> versus children without <i>C. albicans</i> were 5.26 for salivary, 6.69 for plaque, and 6.3 for oral swab samples. This systematic review indicates that children with oral <i>C. albicans</i> have >5 times higher odds of having ECC compared to those without <i>C. albicans</i>. Further prospective cohort studies are needed to determine whether <i>C. albicans </i>could be a risk factor for ECC, and whether it is dependent on different sample sources (saliva/plaque).</p