Semiclassical (Quantum Field Theory) and Quantum (String) de Sitter Regimes: New Results

We compute the quantum string entropy S_s(m, H) from the microscopic string density of states rho_s (m,H) of mass m in de Sitter space-time. We find for high m, a {\bf new} phase transition at the critical string temperature T_s= (1/2 pi k_B)L c^2/alpha', higher than the flat space (Hagedorn) temperature t_s. (L = c/H, the Hubble constant H acts at the transition as producing a smaller string constant alpha' and thus, a higher tension). T_s is the precise quantum dual of the semiclassical (QFT Hawking-Gibbons) de Sitter temperature T_sem = hbar c /(2\pi k_B L). We find a new formula for the full de Sitter entropy S_sem (H), as a function of the usual Bekenstein-Hawking entropy S_sem^(0)(H). For L << l_{Planck}, ie. for low H << c/l_Planck, S_{sem}^{(0)}(H) is the leading term, but for high H near c/l_Planck, a new phase transition operates and the whole entropy S_sem (H) is drastically different from the Bekenstein-Hawking entropy S_sem^(0)(H). We compute the string quantum emission cross section by a black hole in de Sitter (or asymptotically de Sitter) space-time (bhdS). For T_sem ~ bhdS << T_s, (early evaporation stage), it shows the QFT Hawking emission with temperature T_sem ~ bhdS, (semiclassical regime). For T_sem ~ bhdS near T_{s}, it exhibits a phase transition into a string de Sitter state of size L_s = l_s^2/L}, l_s= \sqrt{\hbar alpha'/c), and string de Sitter temperature T_s. Instead of featuring a single pole singularity in the temperature (Carlitz transition), it features a square root branch point (de Vega-Sanchez transition). New bounds on the black hole radius r_g emerge in the bhdS string regime: it can become r_g = L_s/2, or it can reach a more quantum value, r_g = 0.365 l_s.Comment: New original materia

Dynamics of fast pattern formation in porous silicon by laser interference

Patterns are fabricated on 290 nm thick nanostructured porous silicon layers by phase-mask laser interference using single pulses of an excimer laser (193 nm, 20 ns pulse duration). The dynamics of pattern formation is studied by measuring in real time the intensity of the diffraction orders 0 and 1 at 633 nm. The results show that a transient pattern is formed upon melting at intensity maxima sites within a time 1-µs) upon melting induced by homogeneous beam exposure and related to the different scenario for releasing the heat from hot regions. The diffraction efficiency of the pattern is finally controlled by a combination of laser fluence and initial thickness of the nanostructured porous silicon layer and the present results open perspectives on heat release management upon laser exposure as well as have potential for alternative routes for switching applications.Postprint (published version

Semiclassical (QFT) and Quantum (String) anti - de Sitter Regimes: New Results

We compute the quantum string entropy S_s(m, H) from the microscopic string density of states of mass m in Anti de Sitter space-time. For high m, (high Hm -->c/\alpha'), no phase transition occurs at the Anti de Sitter string temperature T_{s} which is higher than the flat space (Hagedorn) temperature t_{s}. (the Hubble constant H acts as producing a smaller string constant and thus, a higher tension). T_s is the precise quantum dual of the semiclassical (QFT) Anti de Sitter temperature scale . We compute the quantum string emission by a black hole in Anti de Sitter space-time (bhAdS). In the early evaporation stage, it shows the QFT Hawking emission with temperature T_{sem~bhAdS}, (semiclassical regime). For T_{sem~bhAdS}--> T_{s}, it exhibits a phase transition into a Anti de Sitter string state. New string bounds on the black hole emerge in the bhAdS string regime. We find a new formula for the full (quantum regime included) Anti de Sitter entropy S_{sem}, as a function of the usual Bekenstein-Hawking entropy S_{sem}^(0). For low H (semiclassical regime), S_{sem}^(0) is the leading term but for high H (quantum regime), no phase transition operates, in contrast to de Sitter space, and the entropy S_{sem} is very different from the Bekenstein-Hawking term S_{sem}^(0).Comment: Comments 26 pages; no figure

Semiclassical (QFT) and Quantum (String) Rotating Black Holes and their Evaporation: New Results

Combination of both quantum field theory (QFT) and string theory in curved backgrounds in a consistent framework, the string analogue model, allows us to provide a full picture of the Kerr-Newman black hole and its evaporation going beyond the current picture. We compute the quantum emission cross section of strings by a Kerr-Newmann black hole (KNbh). It shows the black hole emission at the Hawking temperature T_{sem} in the early evaporation and the new string emission featuring a Hagedorn transition into a string state of temperature T_ s at the last stages. New bounds on the angular momentum J and charge Q emerge in the quantum string regime. The last state of evaporation of a semiclassical KNbh is a string state of temperature T_s, mass M_s, J = 0 = Q, decaying as a quantum string into all kinds of particles.(There is naturally, no loss of information, (no paradox at all)). We compute the microscopic string entropy S_s(m, j) of mass m and spin mode j. (Besides the usual transition at T_s), we find for high j, (extremal string states) a new phase transition at a temperature T_{sj} higher than T_s. We find a new formula for the Kerr black hole entropy S_{sem}, as a function of the usual Bekenstein-Hawking entropy . For high angular momentum, (extremal J = GM^2/c), a gravitational phase transition operates and the whole entropy S_{sem} is drastically different from the Bekenstein-Hawking entropy. This new extremal black hole transition occurs at a temperature T_{sem J} higher than the Hawking temperature T_{sem}.Comment: New articl

Tachyon warm inflationary universe models

Warm inflationary universe models in a tachyon field theory are studied. General conditions required for these models to be realizable are derived and discussed. We describe scalar perturbations (in the longitudinal gauge) and tensor perturbations for these scenarios. We develop our models for a constant dissipation parameter $\Gamma$ in one case and one dependent on $\phi$ in the other case. We have been successful in describing such of inflationary universe models. We use recent astronomical observations for constraining the parameters appearing in our model. Also, our results are compared with their analogous found in the cool inflationary case.Comment: 21 pages, Accepted by JCA

Extended Curvaton reheating in inflationary models

The curvaton reheating in a non-oscillatory inflationary universe model is studied in a Jordan-Brans-Dicke theory. For different scenarios, the temperature of reheating is computed. The result tells us that the reheating temperature becomes practically independent of the Jordan-Brans-Dicke parameter $w$. This reheating temperature results to be quite different when compared with that obtained from Einstein`s theory of gravity.Comment: Accepted by JCAP, 12 pages, 1 Figur

Penetrative Convection Modifies the Dynamics of Downslope Gravity Currents

Abstract Gravity currents contribute to the transport of heat and mass in atmospheric and aquatic environments. In aquatic systems subject to daily surface cooling, gravity currents propagate through turbulent convective surroundings. Yet, the effects of thermal convection on aquatic gravity currents remain to be quantified. This paper demonstrates how the interaction between penetrative convection and downslope gravity currents impacts the fluid dynamics and transport across littoral aquatic systems. We performed field experiments in a wind‐sheltered lake experiencing differential cooling to resolve the dynamics of thermally driven gravity currents in convective environments. Our in situ observations reveal that convective plumes penetrate gravity currents, generating large vertical fluctuations that foster the erosion of the stratified layer. This enhanced vertical mixing destroys the stratified downslope flow and limits the basin‐scale transport. Our results demonstrate that the interaction between penetrative convection and downslope gravity currents controls the littoral‐pelagic connectivity in aquatic ecosystems

Location and course of the mandibular canal in dentate patients: morphometric study using cone-beam computed tomography

Background: The morphometric characteristics of the mandibular canal (MC) may vary according to the characteristics of the population studied. Correct location of the MC is fundamental for the indication and planning of different dental treatments, and it is therefore essential to have clinical parameters indicating its approximate location. The aim of this study was to describe the location and course of the MC by morphometric relations in the mandibular body, from the mental foramen to distal of the first molar, in dentate adult patients. Materials and methods: We analysed 55 cone-beam computed tomography (CBCT) of male and female patients, aged over 18 years and with fully dentate to the first molar. In each CBCT we selected five coronal sections (A–E) of the mandibular body at different levels using the teeth as references. We determined different morphometric measurements in each section to relate the MC with the corticals of the mandibular body (m1, m2, m3, m4), their orientation to lingual (F) and the thickness of the mandibular corticals (B1, B2 and B3). Results: The distance between the MC and the alveolar crests was greater in males than in females in all the sections. In general, in all the hemiarches, the MC courses away from the vestibular cortical of the mandible (and in some cases significantly towards the lingual cortical) from anterior to posterior in the mandibular body. In the left hemiarch of dentate females the MC describes a descent in the molar zone within the mandibular body. Any intervention in the mandible must be carried out with extreme caution to avoid damaging the vasculo-nervous bundle which passes through the MC. Conclusions: Cone-beam computed tomography is the best tool currently available for the planning and execution of surgical procedures, and is the only tool in clinical use which allows the precise course of the MC to be identified

The DEPURANAT project : sustainable management of wastewater in rural areas

The DEPURANATt project received co-financing from the European Union through its interregional cooperation programme, Interreg IIIB Atlantic Arc Programme. This project, coordinated by the Canary Islands Institute of Technology, allowed French, Portuguese and Spanish institutions to work together on sustainable management of wastewater in rural and protected areas. Within the framework of this project, twelve natural wastewater treatment systems have been built or adapted from pre-existing systems in Portugal, Andalusia and the Canary islands. In these systems, a shared ambitious protocol of physical-chemical and microbiological analyses was established, and several studies carried out with respect to the agronomical quality of the effluents and the physiology of the plants. These analytical campaigns also attempted to promote a positive image of these systems to, and in, the rural areas. Moreover, it is important for the target publics to value correctly the possibilities created by regenerated wastewater and vegetal biomass, and thus accept the same as integral methods which contribute to sustainable local development. Several studies relating to social integration were focused, to this end, on measuring people’s acceptance of these systems in their areas, whereas the environmental impact of the systems was determined using an adapted life cycle assessment methodology. The economic analysis of the systems focused on analysing the financial indicators, empirical cost functions, and the potential market for these technologies. Furthermore, maps of potential areas where natural wastewater treatment systems may be implemented have been created. Finally, a support tool for deciding upon the installation of conventional or natural wastewater treatment systems has been designed with the aim of informing at technicians about the most suitable technology to be applied in each situation

Functional statistical techniques applies to vine leaf water content

P. 1116-1122A statistical analysis of functional data, obtained as reflectance values measured using a hyperspectral sensor, was used to determine water content in vine leaves. Our study was conducted using a sample of 80 vine leaves whose water content was determined by calculating the weight difference between leaves before and after drying in an oven.S