Yukawa Unification, b --> s gamma and Bino-Stau Coannihilation

The minimal supersymmetric standard model with universal boundary conditions and "asymptotic" Yukawa unification is considered. The full one-loop effective potential for radiative electroweak symmetry breaking as well as the one-loop corrections to the charged Higgs boson, b-quark and tau lepton masses are included. The CP-even Higgs boson masses are corrected to two-loops. The relic abundance of the lightest supersymmetric particle (bino) is calculated by including its coannihilations with the next-to-lightest supersymmetric particle (lightest stau) consistently with Yukawa unification. The branching ratio of b --> s gamma is evaluated by incorporating all the applicable next-to-leading order QCD corrections. The bino-stau coannihilations reduce the bino relic abundance below the upper bound from cold dark matter considerations in a sizable fraction of the parameter space allowed by b --> s gamma for mu>0. Thus, the mu>0 case, which also predicts an acceptable b-quark mass, is perfectly compatible with data.Comment: 16 pages including 3 figures, Revtex, major revisions are mad

Redefining the role of obstacles in pedestrian evacuation

The placement of obstacles in front of doors is believed to be an effective strategy to increase the flow of pedestrians, hence improving the evacuation process. Since it was first suggested, this counterintuitive feature is considered a hallmark of pedestrian flows through bottlenecks. Indeed, despite the little experimental evidence, the placement of an obstacle has been hailed as the panacea for solving evacuation problems. In this work, we challenge this idea and experimentally demonstrate that the pedestrians flow rate is not necessarily altered by the presence of an obstacle. This result - which is at odds with recent demonstrations on its suitability for the cases of granular media, sheep and mice - differs from the outcomes of most of existing numerical models, and warns about the risks of carelessly extrapolating animal behaviour to humans. Our experimental findings also reveal an unnoticed phenomenon in relation with the crowd movement in front of the exit: in competitive evacuations, an obstacle attenuates the development of collective transversal rushes, which are hazardous as they might cause falls.Fil: Garcimartín, A.. Universidad de Navarra; EspañaFil: Maza, D.. Universidad de Navarra; EspañaFil: Pastor, J. M.. Focke Meler Gluing Solutions S.A.; EspañaFil: Parisi, Daniel Ricardo. Instituto Tecnológico de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martín Gómez, C.. Universidad de Navarra; EspañaFil: Zuriguel, I.. Universidad de Navarra; Españ

A cluster model with random anisotropy for hysteresis jumps in CeNi1−x_{1-x}Cux_{x} alloys

Some Cerium compounds exhibit hysteresis cycles with sharp macroscopic jumps in the magnetization at very low temperatures. This effect is attributed to the formation of clusters in which the anisotropy competes with the applied magnetic field. Here, we present a simple model where a lattice of ferromagnetically coupled spins is separated in clusters of random sizes and with random anisotropy. Within this model, we obtain hysteresis cycles presenting jumps that behave in a similar way that the experimental ones, and that disappear when increasing the temperature. The results are in good agreement with the hysteresis cycles measured at very low temperatures in CeNi$_{1-x}$Cu$_{x}$ and the comparison with these experimental results allows to discriminate the relative importance of the mechanisms driving the thermal evolution of the cycles.Comment: Accepted in PR

A Sustainable Approach for the Downstream Processing of Bacterial Polyhydroxyalkanoates: State-of-the-art and latest developments

Bioplastics have emerged as a platform to reduce our dependence on fossil fuels. Polyhydroxyalkanoates (PHAs) are a family of biodegradable polyesters with large potential in consumer goods and medical applications. These polymers accumulate in prokaryotic microbes and their recovery is a challenging, often under explored, operation. In the past, oil-derived solvents and chemicals have been widely used as extracting agents, compromising the “environmentally-friendly” claim of bioplastics. Furthermore, the large amount of chemicals and solvents required at the industrial level would negatively impact the economics of the process. The present review presents the latest advances in the field of downstream operations for PHA recovery emphasizing those green technologies with scaling-up feasibility. As for the upstream and fermentation stages, the extraction process needs to be carefully optimized to accomplish a competitive production of PHAs

The missing atom as a source of carbon magnetism

Atomic vacancies have a strong impact in the mechanical, electronic and magnetic properties of graphene-like materials. By artificially generating isolated vacancies on a graphite surface and measuring their local density of states on the atomic scale, we have shown how single vacancies modify the electronic properties of this graphene-like system. Our scanning tunneling microscopy experiments, complemented by tight binding calculations, reveal the presence of a sharp electronic resonance at the Fermi energy around each single graphite vacancy, which can be associated with the formation of local magnetic moments and implies a dramatic reduction of the charge carriers' mobility. While vacancies in single layer graphene naturally lead to magnetic couplings of arbitrary sign, our results show the possibility of inducing a macroscopic ferrimagnetic state in multilayered graphene samples just by randomly removing single C atoms.Comment: Accepted for publication in Physical Review Letter

Cognitive differences in the older adults living in the general community: gender and mental occupational state study

Older adults are particularly vulnerable to cognitive impairment with age, and gender differences are remarkable. However, there is very little evidence to identify both baseline cognitive and occupational gender differences prior to older adults’ retirement to design more efficient personalized cognitive interventions. This descriptive observational study examined gender differences in initial cognitive performance in 367 older adults with subjective memory complaints from a primary healthcare center in Zaragoza (Spain). To evaluate initial cognitive performance, the Spanish version of the Mini-Mental State Examination (MEC-35) and the set test were used to measure verbal fluency. Sociodemographic and clinical characteristics were evaluated, and cognitive and occupational differences were analyzed per gender. Men had higher educational and occupational levels, were older and more of them were married (p < 0.001) than women. Regarding cardiovascular risk factors, diabetes and cerebrovascular accidents were more frequent in women, while hypercholesterolemia and obesity were more frequent in men (p < 0.001). High blood pressure was more frequent in women, but not significantly so (p = 0.639). Global cognition was higher in men (p < 0.001) for attention, calculation, and language (p < 0.001). Verbal fluency was higher in women, but the difference was not statistically significant (p = 0.105). These results could be gen-eralized to other health centers in the province and other Spanish autonomous communities as their sociodemographic variables are similar. Individualized interventions that adapt to gender, cognitive and initial occupational performance should be developed and adapted to elderly populations living in the general community to maintain their cognitive capacity and prevent their cognitive impairment and the social health costs this would imply

The milliarcsecond-scale jet of PKS 0735+178 during quiescence

We present polarimetric 5 GHz to 43 GHz VLBI observations of the BL Lacertae object PKS 0735+178, spanning March 1996 to May 2000. Comparison with previous and later observations suggests that the overall kinematic and structural properties of the jet are greatly influenced by its activity. Time intervals of enhanced activity, as reported before 1993 and after 2000 by other studies, are followed by highly superluminal motion along a rectilinear jet. In contrast the less active state in which we performed our observations, shows subluminal or slow superluminal jet features propagating through a twisted jet with two sharp bends of about 90 deg. within the innermost three-milliarcsecond jet structure. Proper motion estimates from the data presented here allow us to constrain the jet viewing angle to values < 9 deg., and the bulk Lorentz factor to be between 2 and 4.Comment: 11 pages, 12 figures. Accepted for publication in A&

The connection between the radio jet and the gamma-ray emission in the radio galaxy 3C 120

We present the analysis of the radio jet evolution of the radio galaxy 3C 120 during a period of prolonged gamma-ray activity detected by the Fermi satellite between December 2012 and October 2014. We find a clear connection between the gamma-ray and radio emission, such that every period of gamma-ray activity is accompanied by the flaring of the mm-VLBI core and subsequent ejection of a new superluminal component. However, not all ejections of components are associated with gamma-ray events detectable by Fermi. Clear gamma-ray detections are obtained only when components are moving in a direction closer to our line of sight.This suggests that the observed gamma-ray emission depends not only on the interaction of moving components with the mm-VLBI core, but also on their orientation with respect to the observer. Timing of the gamma-ray detections and ejection of superluminal components locate the gamma-ray production to within almost 0.13 pc from the mm-VLBI core, which was previously estimated to lie about 0.24 pc from the central black hole. This corresponds to about twice the estimated extension of the broad line region, limiting the external photon field and therefore suggesting synchrotron self Compton as the most probable mechanism for the production of the gamma-ray emission. Alternatively, the interaction of components with the jet sheath can provide the necessary photon field to produced the observed gamma-rays by Compton scattering.Comment: Already accepted for publication in The Astrophysical Journa