Charged rotating noncommutative black holes

In this paper we complete the program of the noncomutative geometry inspired black holes, providing the richest possible solution, endowed with mass, charge and angular momentum. After providing a prescription for employing the Newman-Janis algorithm in the case of nonvanishing stress tensors, we find regular axisymmetric charged black holes in the presence of a minimal length. We study also the new thermodynamics and we determine the corresponding higher-dimensional solutions. As a conclusion we make some consideration about possible applications.Comment: 13 pages, 3 figures, correction of a typesetting inattention, updated reference list, version accepted for publication on Physical Review

Spectral dimension of a quantum universe

In this paper, we calculate in a transparent way the spectral dimension of a quantum spacetime, considering a diffusion process propagating on a fluctuating manifold. To describe the erratic path of the diffusion, we implement a minimal length by averaging the graininess of the quantum manifold in the flat space case. As a result we obtain that, for large diffusion times, the quantum spacetime behaves like a smooth differential manifold of discrete dimension. On the other hand, for smaller diffusion times, the spacetime looks like a fractal surface with a reduced effective dimension. For the specific case in which the diffusion time has the size of the minimal length, the spacetime turns out to have a spectral dimension equal to 2, suggesting a possible renormalizable character of gravity in this regime. For smaller diffusion times, the spectral dimension approaches zero, making any physical interpretation less reliable in this extreme regime. We extend our result to the presence of a background field and curvature. We show that in this case the spectral dimension has a more complicated relation with the diffusion time, and conclusions about the renormalizable character of gravity become less straightforward with respect to what we found with the flat space analysis.Comment: 5 pages, 1 figure, references added, typos corrected, title changed, final version published in Physical Review

Self-completeness and spontaneous dimensional reduction

A viable quantum theory of gravity is one of the biggest challenges facing physicists. We discuss the confluence of two highly expected features which might be instrumental in the quest of a finite and renormalizable quantum gravity -- spontaneous dimensional reduction and self-completeness. The former suggests the spacetime background at the Planck scale may be effectively two-dimensional, while the latter implies a condition of maximal compression of matter by the formation of an event horizon for Planckian scattering. We generalize such a result to an arbitrary number of dimensions, and show that gravity in higher than four dimensions remains self-complete, but in lower dimensions it is not. In such a way we established an "exclusive disjunction" or "exclusive or" (XOR) between the occurrence of self-completeness and dimensional reduction, with the goal of actually reducing the unknowns for the scenario of the physics at the Planck scale. Potential phenomenological implications of this result are considered by studying the case of a two-dimensional dilaton gravity model resulting from dimensional reduction of Einstein gravity.Comment: 12 pages, 3 figures; v3: final version in press on Eur. Phys. J. Plu

A Hermeneutic Phenomenological Study of Teen Mothers Who Graduated from an Alternative School

Many studies support the recurring theme that due to early childbearing, the education of teen mothers is jeopardized. Negative stereotypes towards them also prevail representing the view that teen mothers are wayward, divergent, and burdensome to society. However, there is support from the literature that the majority of them maintain career and educational aspirations. Moreover, access of pregnant minors and teen mothers to public education is guaranteed by law. With this in view, the researcher explored the educational experiences of teen mothers, particularly those who chose to enroll in and eventually graduated from an alternative public school that exclusively serves this population. A hermeneutic phenomenological approach was used in interviewing seven teen mothers who graduated from an alternative school. This qualitative method was useful in understanding subjective experiences, forming insights about individuals’ motivations and actions. The participants were selected by purposive sampling. Inductive analysis of the data indicated that attending an alternative school provided academic reengagement, structure, motivation, and a safe and caring learning environment for the participants. This study makes a contribution to the scant literature about the educational experiences of teen mothers, providing evidence that they strive to succeed and can succeed educationally when given support and access to academic services. The conclusions serve as a counter discourse to the prevailing negative perceptions towards this challenged population

Sub-Planckian black holes and the Generalized Uncertainty Principle

The Black Hole Uncertainty Principle correspondence suggests that there could exist black holes with mass beneath the Planck scale but radius of order the Compton scale rather than Schwarzschild scale. We present a modified, self-dual Schwarzschild-like metric that reproduces desirable aspects of a variety of disparate models in the sub-Planckian limit, while remaining Schwarzschild in the large mass limit. The self-dual nature of this solution under $M \leftrightarrow M^{-1}$ naturally implies a Generalized Uncertainty Principle with the linear form $\Delta x \sim \frac{1}{\Delta p} + \Delta p$. We also demonstrate a natural dimensional reduction feature, in that the gravitational radius and thermodynamics of sub-Planckian objects resemble that of $(1+1)$-D gravity. The temperature of sub-Planckian black holes scales as $M$ rather than $M^{-1}$ but the evaporation of those smaller than $10^{-36}$g is suppressed by the cosmic background radiation. This suggests that relics of this mass could provide the dark matter.Comment: 12 pages, 9 figures, version published in J. High En. Phy

Spinning Loop Black Holes

In this paper we construct four Kerr-like spacetimes starting from the loop black hole Schwarzschild solutions (LBH) and applying the Newman-Janis transformation. In previous papers the Schwarzschild LBH was obtained replacing the Ashtekar connection with holonomies on a particular graph in a minisuperspace approximation which describes the black hole interior. Starting from this solution, we use a Newman-Janis transformation and we specialize to two different and natural complexifications inspired from the complexifications of the Schwarzschild and Reissner-Nordstrom metrics. We show explicitly that the space-times obtained in this way are singularity free and thus there are no naked singularities. We show that the transformation move, if any, the causality violating regions of the Kerr metric far from r=0. We study the space-time structure with particular attention to the horizons shape. We conclude the paper with a discussion on a regular Reissner-Nordstrom black hole derived from the Schwarzschild LBH and then applying again the Newmann-Janis transformation.Comment: 18 pages, 18 figure

Composition ot Glvceride Esters of Lauric Acid bV FTIR Band Shape Analysis

Synthesis of glyceride esters of a fatty acid produces a mixture of isomers that are difficult to separate and analyze, requiring high temperature GC in most cases particularly for long-chain esters. In this paper, we present a fast estimation of the composition of the glyceride esters of lauric acid and glycerol (monolaurin, dilaurin, and trilaurin) by FTIR band shape analysis. The method uses the fact that the carbonyl stretching regions of the pure glycerides have differentband shapes, which implies any composite band of a mixture of glycerides may be resolved into the component peaks due to each glyceride. The carbonyl band region was fitted with five component peaks using a commercial peak-fitting program. The peak at 1745 cm-1 is characteristic of trilaurin whereas the peaks at 1740 cm-1 and 1731 cm-1 provide a unique height ratio for mono- and dilaurin. Calibration curves were prepared and a system of two equations may be solved to obtain the composition of mono-, di-, and trilaurin. This method was tested with known mixtures of the glycerides yielding estimates within ± 10 % composition units

The Hawking-Page crossover in noncommutative anti-deSitter space

We study the problem of a Schwarzschild-anti-deSitter black hole in a noncommutative geometry framework, thought to be an effective description of quantum-gravitational spacetime. As a first step we derive the noncommutative geometry inspired Schwarzschild-anti-deSitter solution. After studying the horizon structure, we find that the curvature singularity is smeared out by the noncommutative fluctuations. On the thermodynamics side, we show that the black hole temperature, instead of a divergent behavior at small scales, admits a maximum value. This fact implies an extension of the Hawking-Page transition into a van der Waals-like phase diagram, with a critical point at a critical cosmological constant size in Plank units and a smooth crossover thereafter. We speculate that, in the gauge-string dictionary, this corresponds to the confinement "critical point" in number of colors at finite number of flavors, a highly non-trivial parameter that can be determined through lattice simulations.Comment: 24 pages, 6 figure, 1 table, version matching that published on JHE

Newtonian gravity as an entropic force: Towards a derivation of G

It has been suggested that the Newtonian gravitational force may emerge as an entropic force from a holographic microscopic theory. In this framework, the possibility is reconsidered that Newton's gravitational coupling constant G can be derived from the fundamental constants of the underlying microscopic theory.Comment: 10 pages. v6: published versio

Dietary Nitrate: Effects on the health of weaning pigs and Antimicrobial activity on seven probiotic Bifidobacterium spp. strains

The potential role of nitrite as an antimicrobial substance in the stomach may be of some importance in the ecology of the gastrointestinal tract and in host physiology. It has been shown that nitrite, under the acidic conditions of the stomach, may kill gut pathogens like Salmonella enteritidis, Escherichia coli, Salmonella typhimurium, and Yersinia enterocolitica, whereas acid alone has only a bacteriostatic effect. An in vivo study was conducted in order to assess the effects of dietary nitrate on microbiota and on the health of the gut (particularly in the stomach and small intestine). 96 weaning pigs were fed a diet containing high nitrate levels (15 mg and 150 mg) and then challenged with Salmonella enterica serovar typhimurium. Differences in composition of the gut microbiota were assessed by analysing samples from the pigs: To date analysis of 48 pigs has been completed.. Preliminary results demonstrated no effect on the population densities of microbial groups either from the challenge or from nitrate intake. However, increasing the time from challenge decreased either the counts of LAB in the stomach and jejunum or of clostridia in the stomach. Bifidobacteria also decreased in the stomach contents as nitrate supplementation increased. Supplementing the feedstuff with high dietary nitrate intake and then challenging with Salmonella did not affect the gastric pH or the degree of ulceration in the pigs. The synergistic bactericidal effects of pH, nitrite and thiocyanate on seven probiotic Bifidobacterium spp. strains were also investigated in an in vitro study. The results of the in vitro study demonstrated that an inhibitory effect exists on the seven probiotic bifidobacteria investigated with an exposure longer than 2 hours and pH values < 5.0. Addition of thiocyanate also increased the susceptibility of the tested strains. In this in vitro study, the most resistant strains at all conditions were B. animalis subsp. lactis Ra 18 and P32 and B. choerinum Su 877, Su 837 and Su 891