Modelization of Thermal Fluctuations in G Protein-Coupled Receptors

We simulate the electrical properties of a device realized by a G protein coupled receptor (GPCR), embedded in its membrane and in contact with two metallic electrodes through which an external voltage is applied. To this purpose, recently, we have proposed a model based on a coarse graining description, which describes the protein as a network of elementary impedances. The network is built from the knowledge of the positions of the C-alpha atoms of the amino acids, which represent the nodes of the network. Since the elementary impedances are taken depending of the inter-nodes distance, the conformational change of the receptor induced by the capture of the ligand results in a variation of the network impedance. On the other hand, the fluctuations of the atomic positions due to thermal motion imply an impedance noise, whose level is crucial to the purpose of an electrical detection of the ligand capture by the GPCR. Here, in particular, we address this issue by presenting a computational study of the impedance noise due to thermal fluctuations of the atomic positions within a rhodopsin molecule. In our model, the C-alpha atoms are treated as independent, isotropic, harmonic oscillators, with amplitude depending on the temperature and on the position within the protein (alpha-helix or loop). The relative fluctuation of the impedance is then calculated for different temperatures.Comment: 5 pages, 2 figures, Proceeding of the 18-th International Conference on Fluctuations and Noise, 19-23 September 2005, Salamanca, Spain -minor proofreadings

Shot Noise in Linear Macroscopic Resistors

We report on a direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. Present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.Comment: 10 pages, 5 figure

A New Lithospheric Density and Magnetic Susceptibility Model of Iran, Starting From High‐Resolution Seismic Tomography

We propose a new model for the crust and upper mantle in Iran by joint inversion of gravity and magnetic fields, constrained with a seismic tomography model. We then calculate shear modulus from the Vs velocities and densities. The crust and mantle tomography model is first converted to a density cube through empirical and petrological velocity-density relations. The starting susceptibility is assigned to a two-layer homogeneous model, above a heat flow-derived Curie depth. Considering the uncertainties in the density-velocity relations, and the starting layered susceptibility variation, we refine the model by a constrained inversion of the gravity and magnetic fields with a Bayesian approach, producing the final 3D density and susceptibility model. The area is tectonically active with high seismicity and active faulting which are regulated by the crustal density and rigidity variations. Higher rigidity matches lower seismicity and extended deserts and basins, suggesting the control of their development. The Neo-Tethys suture, extending similar to 1,500 km long, as well as the Paleo-Tethys suture match crustal scale density variations, defining characteristics of the lighter Arabian plate and denser Eurasian crust. The South Caspian Basin is enigmatic, due to focusing on the seismicity along all its borders, but with relatively low average rigidity, which is contrary to what is observed for Iran, where the reduced rigidity correlates with higher seismicity. The 3D density model will be useful for numerical geodynamic models and obtaining geologic inferences from the crustal-scale units. The inversion of potential fields may produce inconsistent results, since there are always multiple models that resolve the anomalies, and the use of other geophysical data sets is necessary. To resolve the problem, we extract information from a high-resolution seismic tomography. With seismic velocities and defining the different layers of the model, using data available in the literature, we realize an a-priori model, on which we perform a Bayesian joint gravity and magnetic inversion, to obtain a final 3D model of the Iranian lithosphere, with a detailed distribution of densities and susceptibilities. With density and velocity values, we also calculate the rigidity of the area. We then compare the models obtained, with geological and tectonic information of the area, observing how density and susceptibility distribution reproduce the position of the magmatic outcrops and the principal tectonic lineaments, indicating the position of the Neo-Tethyan and Paleo-Tethyan sutures. Also, the rigidity model is consistent with the seismicity distribution of the area. 3D Bayesian joint inversion builds a reliable model of the lithosphere in the Iranian collision belt, useful for rheological calculationsMost of the magmatic and tectonic features can be followed by density variations in the crust, partly extending to the lower crustJointly with the seismic Vs tomography, rigidity is obtained which explains the inhomogeneous distribution of seismicity in the are

Veterinaria práctica: Un caso de fluxión periódica

El día 11 de Junio ingresó al Hospital un caballo zaino del señor R. Vivar. Antecedentes.— Hacía ya cuatro días que el animal se hallaba triste, sin apetito, con un lagrimeo abundante. El enfermo fué traído de un potrero, donde se habían muerto días anteriores tres animales, que según el propietario presentaban los mismos síntomas que el presente caso.Facultad de Ciencias Agrarias y Forestale

Veterinaria práctica: Un caso de fluxión periódica

El día 11 de Junio ingresó al Hospital un caballo zaino del señor R. Vivar. Antecedentes.— Hacía ya cuatro días que el animal se hallaba triste, sin apetito, con un lagrimeo abundante. El enfermo fué traído de un potrero, donde se habían muerto días anteriores tres animales, que según el propietario presentaban los mismos síntomas que el presente caso.Facultad de Ciencias Agrarias y Forestale

Ruptura del biceps

Descripción de caso clínico de un caballo que claudicaba del miembro anterior izquierdo, con antecedentes de cólicos por coprostasis.Facultad de Ciencias Agrarias y Forestale

Ruptura del biceps

Descripción de caso clínico de un caballo que claudicaba del miembro anterior izquierdo, con antecedentes de cólicos por coprostasis.Facultad de Ciencias Agrarias y Forestale

Deployment and design of multiantenna solutions for fixed WiMAX systems

WiMax has already attracted the attention of operators and manifacturing industries for its promise of large throughput and coverage in broadband wireless access. However, towards the goal of an efficient deployment of this technology, a thorough analysis of its performance in presence of frequency reuse under realistic traffic conditions is mandatory. In particular, an important performance limiting factor is the inter-cell interference, which has strong non-stationary features. This paper investigates the deployment of multi-antenna base stations and the related design of signal processing algorithms for interference mitigation, for the uplink of IEEE 802.16-2004 systems. Extensive numerical results for realistic interference models show the advantages of the proposed multi-antenna system

Studio della quota di volo mediante GNSS, altimetro radar e barometro per rilievi di spettroscopia gamma da velivolo

Lo studio della distribuzione dei radionuclidi terrestri (238U, 232Th e 40K) realizzato mediante tecniche di spettroscopia gamma da velivolo è influenzato dalla quota a cui il rivelatore si trova rispetto al suolo. Un'incertezza del 10% a 100 m di altezza origina un errore nella stima del segnale gamma del 208Tl, appartenente alla catena di decadimenti del 232Th, dell’ordine del 7%. L'impiego di una nuova classe di spettrometri montati a bordo di UAV (Unmanned Aerial Vehicle) per raffinate misure in contesti ostili o remoti rende necessaria un'accurata stima in real time della quota di volo. Il Radgyro è un velivolo dedicato a survey multiparametrici, capace di trasportare strumentazione pari ad un payload massimo di 120 kg, tra cui quattro spettrometri gamma NaI(Tl). Una stazione inerziale con ricevitore integrato GNSS (Global Navigation Satellite System) restituisce l'assetto del velivolo con una frequenza massima di 400 Hz. Il velivolo è dotato di un network di tre ricevitori GNSS posizionati alle estremità della carena del velivolo. Un altimetro radar a 24 GHz rileva la quota con una frequenza di 60 Hz. La misura di pressione e temperatura consente di ricavare la quota barometrica a 2 Hz. Con l'obiettivo di studiare le incertezze associate alle misure della quota di volo acquisite dagli altimetri in relazione ai dati GNSS, sono stati realizzati tre voli sul mare in un range di altezze comprese tra 31 m e 249 m, per un totale di 4702 secondi di volo effettivo. Al termine dello studio è possibile concludere che l'errore complessivo delle abbondanze di K, U e Th aumenta di 7.7%, 0.5% e 2.7% rispettivamente, a causa delle incertezze della quota di volo