A two-dimensional doppler-radiometer for earth observation

Compared to synthetic aperture radars (SARs), the angular resolution of microwave radiometers is quite poor. Traditionally, it has been limited by the physical size of the antenna. However, the angular resolution can be improved by means of aperture synthesis interferometric techniques. A narrow beam is synthesized during the image formation processing of the cross-correlations measured at zero-lag between pairs of signals collected by an array of antennas. The angular resolution is then determined by the maximum antenna spacing normalized to the wavelength (baseline). The next step in improving the angular resolution is the Doppler-Radiometer, somehow related to the super-synthesis radiometers and the Radiometer-SAR. This paper presents the concept of a three-antenna Doppler-Radiometer for 2D imaging. The performance of this instrument is evaluated in terms of angular/spatial resolution and radiometric sensitivity, and an L-band illustrative example is presented.

Manipulació geomètrica dels blocs d'AutoCAD

Aquest text és un recull de procediments per inserir els blocs d'AutoCAD de forma més eficient, en la resolució de problemes prèviament tipificats: la PRIMERA PART descriu protocols d'actuació que l'usuari haurà d'aplicar manualment, mentre que la SEGONA PART ofereix rutines programades en AutoLISP i VisualLISP que l'eximiran d'aquesta obligació.Si ho deixéssim aquí, però, podria semblar que els mateixos mètodes manuals presentats en primer lloc són després els que AutoLISP automatitza; per això convé aclarir que la problemàtica de la PRIMERA PART, tot i que pròxima a la de la SEGONA, és diferent i reprodueix el contingut d'una monografia (BLOCS I GEOMETRIA: 5 EXERCICIS COMENTATS) que forma part del material de suport a l'assignatura ELEMENTS DE CAD, impartida per l'autor en l'ETS d'Enginyeria de Telecomunicació de Barcelona i que té per objecte cobrir el buit bibliogràfic que es detectava en el vessant geomètric de la inserció de blocs, a diferència del que s'ocupa de l'estructura de dades més adient en cada context (incrustació de dibuixos amb INSERT versus vinculació mitjançant REFX), més profusament tractat, proposant una sistematització tipològica dels casos on l'escala és funció lineal d'una distància.La SEGONA PART va més enllà i amplia el repertori d'AutoCAD amb les ordres GINSERT, RATREDIT, INSERTOK, INS2D, INS3D, BLOQUEOK, DESCOMPOK, DEF-TRANSF, APL-TRANSF-V i APL-TRANSF-N, de les quals INS2D i INS3D (INSERTOK és una versió simplificada de INS2D, per a blocs sense atributs) són l'aportació més innovadora i que més lluny porta les potencialitats de la inserció de blocs: resumint-ho en una frase, es tracta d’aconseguir que la inserció d’un bloc (que pot ser l’original, un bloc constituït per una inserció de l’original o un de constituït per la inserció del precedent) s’encabeixi en un marc prèviament establert, a semblança de les ordres ESCALA o GIRA, que mitjançant l'opció Referencia apliquen als objectes seleccionats la transformació d'escalat o de rotació necessària per tal que un element de referència assoleixi una determinada grandària o posició. Tot i que, per identificar amb encert el nucli del problema, serà inevitable introduir una reflexió: quan s’ha tingut la precaució de referir un bloc 2D a un quadrat unitari ortogonal, inserir-lo de manera que s’adapti a qualsevol marc rectangular establert en el dibuix és immediat, però ja no ho és tant concatenar insercions de manera que, a més d’una combinació simple de escalat, gir i translació, l’operació dugui implícita una transformació de cisallament. Perquè és clar que si inserim el bloc girat i convertim la inserció en un bloc que al seu torn tornem a inserir, ara però amb escalat no uniforme, el transformat del quadrat de referència primitiu serà un paral·lelogram, però el problema és: dibuixat un marc romboïdal concret, ¿quin gir caldrà donar a la primera inserció, i quin gir i factors d’escala caldrà aplicar a la segona perquè el quadrat de referència s’adapti al marc? El problema es complica si, a més, volem aprofitar el resultat de la primera inserció per a d’altres paral·lelograms, organitzant un sistema no redundant de insercions intermèdies. Doncs bé: INS2D i INS3D donen satisfacció a aquestes qüestions (la segona ja no contempla l'encaix en un paral·lelogram, sinó en un paral·lelepípede) i són aplicables a blocs proveïts d’atributs, no només de tipus convencional (els continguts en el pla de base del bloc, únics de funcionament garantit amb l’ordre INSERT), sinó també dels situats i orientats lliurement.

Perception of acceleration in motion-in-depth with only monocular and both monocular and binocular information

Observers are often required to adjust actions with objects that change their speed. However, no evidence for a direct sense of acceleration has been found so far. Instead, observers seem to detect changes in velocity within a temporal window when confronted with motion in the frontal plane (2D motion). Furthermore, recent studies suggest that motion-in-depth is detected by tracking changes of position in depth. Therefore, in order to sense acceleration in depth a kind of second-order computation would have to be carried out by the visual system. In two experiments, we show that observers misperceive acceleration of head-on approaches at least within the ranges we used [600-800 ms] resulting in an overestimation of arrival time. Regardless of the viewing condition (only monocular or monocular and binocular), the response pattern conformed to a constant velocity strategy. However, when binocular information was available, overestimation was highly reduced.

Protein oligomers studied by solid-state NMR the case of the full-length nucleoid-associated protein histone-like nucleoid structuring protein

Members of the histone-like nucleoid structuring protein (H-NS) family play roles both as architectural proteins and as modulators of gene expression in Gram-negative bacteria. The H-NS protein participates in modulatory processes that respond to environmental changes in osmolarity, pH, or temperature. H-NS oligomerization is essential for its activity. Structural models of different truncated forms are available. However, high-resolution structural details of full-length H-NS and its DNA-bound state have largely remained elusive. We report on progress in characterizing the biologically active H-NS oligomers with solid-state NMR. We compared uniformly ((13)C,(15)N)-labeled ssNMR preparations of the isolated N-terminal region (H-NS 1-47) and full-length H-NS (H-NS 1-137). In both cases, we obtained ssNMR spectra of good quality and characteristic of well-folded proteins. Analysis of the results of 2D and 3D (13)C-(13)C and (15)N-(13)C correlation experiments conducted at high magnetic field led to assignments of residues located in different topological regions of the free full-length H-NS. These findings confirm that the structure of the N-terminal dimerization domain is conserved in the oligomeric full-length protein. Small changes in the dimerization interface suggested by localized chemical shift variations between solution and solid-state spectra may be relevant for DNA recoginition.

Sustained CTL activation by murine pulmonary epithelial cells promotes the development of COPD-like disease

Chronic obstructive pulmonary disease (COPD) is a lethal progressive lung disease culminating in permanent airway obstruction and alveolar enlargement. Previous studies suggest CTL involvement in COPD progression; however, their precise role remains unknown. Here, we investigated whether the CTL activation receptor NK cell group 2D (NKG2D) contributes to the development of COPD. Using primary murine lung epithelium isolated from mice chronically exposed to cigarette smoke and cultured epithelial cells exposed to cigarette smoke extract in vitro, we demonstrated induced expression of the NKG2D ligand retinoic acid early tran - script 1 (RAET1)as well as NKG2D-mediated cytotoxicity. Furthermore, a genetic model of inducible RAET1 expression on mouse pulmonary epithelial cells yielded a severe emphysematous phenotype characterized by epithelial apoptosis and increased CTL activation, which was reversed by blocking NKG2D activation. We also assessed whether NKG2D ligand expression corresponded with pulmonary disease in human patients by staining airway and peripheral lung tissues from never smokers, smokers with normal lung function, and current and former smokers with COPD. NKG2D ligand expression was independent of NKG2D receptor expression in COPD patients, demonstrating that ligand expression is the limiting factor in CTL activation. These results demonstrate that aberrant, persistent NKG2D ligand expression in the pulmonary epithelium contributes to the development of COPD pathologies.

Particle shape and orientation in laser diffraction and static image analysis size distribution analysis of micrometer sized rectangular particles

Laser diffraction (LD) and static image analysis (SIA) of rectangular particles [United States Pharmacopeia, USP30-NF25, General Chapter <776>, Optical Miroscopy.] have been systematically studied. To rule out sample dispersion and particle orientation as the root cause of differences in size distribution profiles, we immobilize powder samples on a glass plate by means of a dry disperser. For a defined region of the glass plate, we measure the diffraction pattern as induced by the dispersed particles, and the 2D dimensions of the individual particles using LD and optical microscopy, respectively. We demonstrate a correlation between LD and SIA, with the scattering intensity of the individual particles as the dominant factor. In theory, the scattering intensity is related to the square of the projected area of both spherical and rectangular particles. In traditional LD the size distribution profile is dominated by the maximum projected area of the particles (A). The diffraction diameters of a rectangular particle with length L and breadth B as measured by the LD instrument approximately correspond to spheres of diameter ØL and ØB respectively. Differences in the scattering intensity between spherical and rectangular particles suggest that the contribution made to the overall LD volume probability distribution by each rectangular particle is proportional to A2/L and A2/B. Accordingly, for rectangular particles the scattering intensity weighted diffraction diameter (SIWDD) explains an overestimation of their shortest dimension and an underestimation of their longest dimension. This study analyzes various samples of particles whose length ranges from approximately 10 to 1000 μm. The correlation we demonstrate between LD and SIA can be used to improve validation of LD methods based on SIA data for a variety of pharmaceutical powders all with a different rectangular particle size and shape.

Microwave spectrometry for the Evaluation of the structural integrity of metallic stents

Purpose: To assess the feasibility of a method based on microwave spectrometry to detect structural distortions of metallic stents in open air conditions and envisage the prospects of this approach toward possible medical applicability for the evaluation of implanted stents. Methods: Microwave absorbance spectra between 2.0 and 18.0 GHz were acquired in open air for the characterization of a set of commercial stents using a specifically design setup. Rotating each sample over 360º, 2D absorbance diagrams were generated as a function of frequency and rotation angle. To check our approach for detecting changes in stent length (fracture) and diameter (recoil), two specific tests were performed in open air. Finally, with a few adjustments, this same system provides 2D absorbance diagrams of stents immersed in a water-based phantom, this time over a bandwidth ranging from 0.2 to 1.8 GHz. Results: The authors show that metallic stents exhibit characteristic resonant frequencies in their microwave absorbance spectra in open air which depend on their length and, as a result, may reflect the occurrence of structural distortions. These resonances can be understood considering that such devices behave like dipole antennas in terms of microwave scattering. From fracture tests, the authors infer that microwave spectrometry provides signs of presence of Type I to Type IV stent fractures and allows in particular a quantitative evaluation of Type III and Type IV fractures. Recoil tests show that microwave spectrometry seems able to provide some quantitative assessment of diametrical shrinkage, but only if it involves longitudinal shortening. Finally, the authors observe that the resonant frequencies of stents placed inside the phantom shift down with respect to the corresponding open air frequencies, as it should be expected considering the increase of dielectric permittivity from air to water. Conclusions: The evaluation of stent resonant frequencies provided by microwave spectrometry allows detection and some quantitative assessment of stent fracture and recoil in open air conditions. Resonances of stents immersed in water can be also detected and their characteristic frequencies are in good agreement with theoretical estimates. Although these are promising results, further verifica tion in a more relevant phantom is required in order to foresee the real potential of this approach.

Oxidative stress in aging: advances in proteomic approaches

Aging is a gradual, complex process in which cells, tissues, organs, and the whole organism itself deteriorate in a progressive and irreversible manner that, in the majority of cases, implies pathological conditions that affect the individual"s Quality of Life (QOL). Although extensive research efforts in recent years have been made, the anticipation of aging and prophylactic or treatment strategies continue to experience major limitations. In this review, the focus is essentially on the compilation of the advances generated by cellular expression profile analysis through proteomics studies (two-dimensional [2D] electrophoresis and mass spectrometry [MS]), which are currently used as an integral approach to study the aging process. Additionally, the relevance of the oxidative stress factors is discussed. Emphasis is placed on postmitotic tissues, such as neuronal, muscular, and red blood cells, which appear to be those most frequently studied with respect to aging. Additionally, models for the study of aging are discussed in a number of organisms, such as Caenorhabditis elegans, senescence-accelerated probe-8 mice (SAMP8), naked mole-rat (Heterocephalus glaber), and the beagle canine. Proteomic studies in specific tissues and organisms have revealed the extensive involvement of reactive oxygen species (ROS) and oxidative stress in aging.

Disseny i implementació d’un joc de plataformes basat en la música

L’objectiu del projecte és crear un videojoc de plataformes d’scroll automàtic en 2D basat en la música. Això vol dir que tots els elements de l’escenari i els moviments que haurà de fer el jugador per a passar-se’l estaran íntegrament lligats a la banda sonora de la pantalla. A més, el joc ha de ser compatible per als dispositius Android

Anàlisi de les tensions de xoc en una llanta de bicicleta

El “llantasso” és un fenomen que es produeix quan, mentre es circula en bicicleta,s’impacta fortament contra un esgraó o un obstacle de manera que tot l’aire contingut dins elpneumàtic es comprimeix. Si això succeeix, el pneumàtic contacta directament amb la llantai l’esgraó, essent l’únic element que els separa. És en aquest instant quan es produeixenunes tensions molt elevades sobre la llanta, les quals en són perjudicials estructuralment.En el present projecte s’han determinat analíticament aquestes tensions quan labicicleta circula a una velocitat de 5 m/s (18 km/h) i impacta contra un esgraó de 15 cmd’alçada. Es volia determinar si l’impacte arribava a produir deformació plàstica permanentde la llanta o si arribava a trencar-se completament.A més a més, també s’ha estudiat quina és la velocitat màxima a la qual pot circular labicicleta per tal que no es produeixi deformació plàstica permanent de la llanta, és a dir, queno es superi el límit elàstic del material.Es tracta d’un projecte totalment teòric, realitzat a través de programes informàtics. Enun primer pas s’ha dibuixat la bicicleta i el ciclista en AutoCAD per poder-ne fer la simulacióen el programa Working Model 2D i obtenir la força màxima que actua sobre la llanta en elmoment de l’impacte

Classification of textures seen from different distances and under varying illumination direction

Changes in the angle of illumination incident upon a 3D surface texture can significantly alter its appearance, implying variations in the image texture. These texture variations produce displacements of class members in the feature space, increasing the failure rates of texture classifiers. To avoid this problem, a model-based texture recognition system which classifies textures seen from different distances and under different illumination directions is presented in this paper. The system works on the basis of a surface model obtained by means of 4-source colour photometric stereo, used to generate 2D image textures under different illumination directions. The recognition system combines coocurrence matrices for feature extraction with a Nearest Neighbour classifier. Moreover, the recognition allows one to guess the approximate direction of the illumination used to capture the test image

Visual SLAM for 3D large-scale seabed acquisition employing underwater vehicles

This paper presents a novel technique to align partial 3D reconstructions of the seabed acquired by a stereo camera mounted on an autonomous underwater vehicle. Vehicle localization and seabed mapping is performed simultaneously by means of an Extended Kalman Filter. Passive landmarks are detected on the images and characterized considering 2D and 3D features. Landmarks are re-observed while the robot is navigating and data association becomes easier but robust. Once the survey is completed, vehicle trajectory is smoothed by a Rauch-Tung-Striebel filter obtaining an even better alignment of the 3D views and yet a large-scale acquisition of the seabed