Restrictions on the coherence of the ultrafast optical emission from an electron-hole pairs condensate

We report on the transfer of coherence from a quantum-well electron-hole condensate to the light it emits. As a function of density, the coherence of the electron-hole pair system evolves from being full for the low density Bose-Einstein condensate to a chaotic behavior for a high density BCS-like state. This degree of coherence is transfered to the light emitted in a damped oscillatory way in the ultrafast regime. Additionally, the photon field exhibits squeezing properties during the transfer time. We analyze the effect of light frequency and separation between electron and hole layers on the optical coherence. Our results suggest new type of ultrafast experiments for detecting electron-hole pair condensation.Comment: 4 pages,3 figures, to be published in Physical Review Letters. Minor change

Black Hole Monodromy and Conformal Field Theory

The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the "hidden conformal symmetry" of a non-extremal black hole, and it explains why features of the inner event horizon appear in scattering data such as greybody factors. This indicates that hidden conformal symmetry is generic within a universality class of black holes.Comment: 20 pages, v2 minor corrections, updated reference

Diplomado de profundización cisco prueba de habilidades prácticas CCNP

El presente trabajo se desarrolla con la finalidad de optar por el título de Ingeniero de Telecomunicaciones y/o Electrónica, de la Universidad nacional Abierta y a Distancia UNAD de Colombia, mediante el desarrollo del Diplomado CISCO, para ellos se debe implementar las habilidades practicas CCNP, mediante el uso de un simulador llamado GNS3 el cual simula Redes reales A partir de Escenarios Propuestos en la guía de actividades, donde primero solicita realizar la configuración de protocolos de conmutación y luego establecer enrutamiento entre la LAN y una IPS, dando así como resultado la posibilidad de comunicarse entre sí, con ello lo que podemos decir es que gracias a este trabajo podemos simular escenarios a los cuales podríamos enfrentarnos como futuros ingenieros.the present work is developed with the purpose of opting for the title of Telecommunications and/or Electronics Engineer, of the National Open and Distance University UNAD of Colombia, through the development of the CISCO Diploma, for them the practical skills CCNP must be implemented, through the use of a simulator called GNS3 which simulates real networks From Proposed Scenarios in the activity guide, where it first requests to configure the switching protocols and then establish routing between the LAN and an IPS, thus resulting in the possibility of communicating with each other, with this what we can say is that thanks to this work we can simulate scenarios that we could face as future engineers

The synthesis of novel precursors for the CVD of antimony sulphide and antimony sulpho-iodide thin films

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Extraction of wood compounds by use of subcritical fluids

A study of the extraction of oak wood compounds with subcritical water-ethanol mixtures as extractant, with an ethanol content between 0-60%, is reported. Identification and characterisation of the extracted compounds have been made by spectrophotometry and gas chromatography with either flame ionisation or mass detectors. Extraction was performed statically manner by use of a single cycle or repeated cycles. All variables affecting the extraction process were studied and optimised. Extraction time and temperature are 60 min and 200ºC, respectively. Comparison of the extract thus obtained with commercial extracts showed the former to be rich in compounds characteristic of the commercial extracts. The method enables manipulation of the extract composition by changing the temperature and water/ethanol ratio used. It is faster than the traditional procedures for obtaining wood extracts

Two-parameter determination in vinegar by a flow injection-pervaporation system

A flow-injection method (FI) for the sequential determination of ethanol and acetic acid in vinegar is reported. The determination of ethanol is based on the oxidation of the pervaporated ethanol by Cr2O7K2. The acetic acid is determined by an acid-base reaction with Thymol Blue as the indicator. Both reactions are monitored photometrically at 600 nm using a single detector. Optimisation studies and assessment of the sequential FI method are also reported. The linear determination range is between 0-12 % (v/v) for ethanol and 0-10 % (grams of acetic acid in 100 ml) for acetic acid. The sample throughput of the sequential manifold is 7 per hour. The new method has been applied to vinegar samples and the results obtained are in excellent agreement with those from the reference methods used in Spain

Semiautomatic flow-injection method for the determination of volatile acidity in wines

A flow-injection (FI) method based on analytical pervaporation was assessed for its routine use in the determination of volatile acidity in winery laboratories. The new method was compared with both the official method and the Mathieu method, which is most often used in Spanish wineries, by testing 30 different wines, including young and aged, and sweet and dry wines from Montilla-Moriles appellation d´origine. The robustness of the new method was established and then all three methods were studied in terms of range of linearity and regression of the calibration curve, repeatability, reproducibility, sensitivity, detection and quantification limits (LOD and LQ, respectively) and time of analysis. The FI method surpasses the Mathieu method in reproducibility and both the Mathieu and official methods in LOD and LQ and sensitivity; it also requires less personnel involvement and shorter analysis time. The statistical criteria established by the “Office International de la Vigne et du Vin” were applied to the data and the results obtained indicated that the differences between the analytical parameters of the 3 methods are not significant and can be applied indistinctly. The correlation of the methods was studied by taking them 2 by 2, and the corresponding equations, coefficients and deviations confirmed the statistical results. Thus, the new method can be used in winery laboratories with clear advantages over its 2 counterparts (the routine and official methods)

Superheated liquids for the extraction of solid residues from winemaking processes

Solid residues from winemaking process have been subjected to extraction with superheated water-ethanol mixtures. Identification and characterisation of the extracted compounds have been made by spectrophotometry, gas chromatography with either flame ionisation or mass detectors and high performance liquid chromatography with UV detection. The extraction has been performed in a static manner by single or repetitive cycles. All variables affecting the extraction process have been studied and optimised. The extraction time and temperature are 65 min and 210ºC, respectively. Two phases constitute the extract: an aqueous phase, which is rich in phenol compounds and an oily phase, mainly formed by fatty acids. The method allows manipulation of the extract composition by changing the applied pressure, temperature, water-ethanol ratio and pH. The method is faster than the traditional extraction procedures for obtaining valuable compounds from these residues