Anderson transition in systems with chiral symmetry

Anderson localization is a universal quantum feature caused by destructive interference. On the other hand chiral symmetry is a key ingredient in different problems of theoretical physics: from nonperturbative QCD to highly doped semiconductors. We investigate the interplay of these two phenomena in the context of a three-dimensional disordered system. We show that chiral symmetry induces an Anderson transition (AT) in the region close to the band center. Typical properties at the AT such as multifractality and critical statistics are quantitatively affected by this additional symmetry. The origin of the AT has been traced back to the power-law decay of the eigenstates; this feature may also be relevant in systems without chiral symmetry.Comment: RevTex4, 4 two-column pages, 3 .eps figures, updated references, final version as published in Phys. Rev.

Landscapes of the Self: The Cinema of Ross McElwee / Paisajes del yo. El cine de Ross McElwee

A book about the films of American documentary filmmaker Ross McElwee. The book is in ENGLISH and SPANISH. The book opens with an ”Establishing Shot,” a prologue presenting an edited ver¬sion of an article published in 1994 by Stephen Rodrick, which sketches out a lively portrait of McElwee. In the second section, we sought greater depth of field. This is our “Wide angle”, with four transversal studies of McElwee’s filmography. First, Efrén Cuevas addresses the most explicitly autobiographical dimension of his films. Alberto N. García presents a study of Ross McElwee as an essayist. The voice-over forms the central topic of Dominique Bluher’s article. Josep María Catalá reflects on the role of the camera in McElwee’s ouvreu, and from this basis, goes on to work out a wider interpretation of McElwee’s intentions. The third section of the book turns to the “Close Up” in order to focus on each of the four autobiographical feature films made by McElwee. It begins with James H. Watkins’s analysis of Sherman’s March. In the next chapter, on Time Indefinite, Paloma Aten¬cia concentrates on how McElwee uses all the autobiographical elements to con-struct an identity understood in narrative terms. Gonzalo de Pedro examines the interesting reflections which Six O’Clock News offers on the relations between television and film. Finally, Gary Hawkins analyzes Bright Leaves from a very personal perspective, that of his double career as critic and documentary filmmaker. The book ends with a “mirror shot” in which Ross McElwee speaks in his own voice. First, we reproduce the only long text that he has written on his own work, “Finding a Voice,” published in 1995 by the French magazine Trafic. To finish, we include a collage of questions and answers from various interviews that he has given over the years

The BSRN twin-stations: IZAÑA (IZA) and SANTA CRUZ (SCO)

Comunicación presentada en: 11th BSRN Scientific Review and Workshop celebrado del 13 al 16 de abril de 2010 en Queenstown, Nueva Zelanda

Variación anual de la concentración de aeropolen de Compositae en la atmósfera de Córdoba

La familia Composirae corwi tU)'C un grupo CU)'OS representantes son cntomófilas, por ello las concentraciones deted adas en la atmósfera han sido bajas. El muestreo se llevó a cabo en Córdoba durante los años 1982. 1983 y 1984 mediante un mucstrcador BURKARD sporc-trap colccado a unos 15m de altura. Se han reconocido un total de 7 tí pos morfológico!> de granos de polen pertenecientes a esta ramilia: tipo Aruflemis,Artemisia, Clutaurea, tipo fleliam! tuJ, Iipo Taraxawm, Srneáo yXa11lhium. Las mayorcscantidadm. tic granos de polen de· teClados pertenecen al tipo l!t !illntlzus, considerados como alergcnos por algunos autores. Sus altas conccnt.radoncs en el aire, en la época de. rccolc.cción del girasol, hace que posiblemente tenga alguna importanci<~ e~~ las polinosis cslivalu. Se han detectado granos de polen. de procedencia lejana, deArtemi.fia, planta con polen ahamenlc alcrgógcno, por tanto pueda ser causa de polioosis de verano en aquellas zonils de !a pro\'incia donde es abundanlcThc Composírae bclong 10 a broad systcmatic group allhough, duc to rhe cntomophylous charactcr of thc spccics, the pollcn conccnltations of lhc samplcs in thc atmosphcrc in thc city of Córdob3 were not beco vcry high. Sampling of poli en grains was e<1rricd out for thrcc ycars (1982, 1983 and 1984) by n1eans ola Burkard sporc- trap samplcr locatcd about t5 m abovc ground leve!. Scvcn morphologica1 typcs of rollen grain~ wcrc recognizcd: AnOzemir, Artemisia, Ccntaurcu typc, Helianrhus typ::, Toraxocum, Su:r:cio and Xanrhium rypc~. Thc largeSI annual amounts of poUeo glilins U::tcclcd wcrc of Hefiamlms typ:, considcrcd allcrgcnic by many authors. Thc higl1er lc-.·els in thc a.ir (ounU duriog tbc. harvcsling scason of sunflowcrs may be rc.spansible for summcr pollinoscs. Arlt misia pollcn g.rains dcvcloping far from thc sampling point wcrc dctcctc:d. Thcsc !.pccics are probably responsible for parl of summcr polli noses duc lo their higb aJlergenic polcntial, at lcast in thc arcas whcrc this plant is abundan!

Spectral aerosol optical depth retrievals by ground-based fourier transform infrared spectrometry

Aerosol Optical Depth (AOD) and the Ångström Exponent (AE) have been calculated in the near infrared (NIR) and short-wave infrared (SWIR) spectral regions over a period of one year (May 2019–May 2020) at the high-mountain Izaña Observatory (IZO) from Fourier Transform Infrared (FTIR) solar spectra. The high-resolution FTIR measurements were carried out coincidentally with Cimel CE318-T photometric observations in the framework of the Aerosol Robotic Network (AERONET). A spectral FTIR AOD was generated using two different approaches: by means of the selection of seven narrow FTIR micro-windows (centred at 1020.90, 1238.25, 1558.25, 1636.00, 2133.40, 2192.00, and 2314.20 nm) with negligible atmospheric gaseous absorption, and by using the CE318-AERONET’s response function in the near-coincident bands (1020 nm and 1640 nm) to degrade the high-resolution FTIR spectra. The FTIR system was absolutely calibrated by means of a continuous Langley–Plot analysis over the 1-year period. An important temporal drift of the calibration constant was observed as a result of the environmental exposure of the FTIR’s external optical mirrors (linear degradation rate up to 1.75% month−1). The cross-validation of AERONET-FTIR databases documents an excellent agreement between both AOD products, with mean AOD differences below 0.004 and root-mean-squared errors below 0.006. A rather similar agreement was also found between AERONET and FTIR convolved bands, corroborating the suitability of low-resolution sunphotometers to retrieve high-quality AOD data in the NIR and SWIR domains. In addition, these results demonstrate that the methodology developed here is suitable to be applied to other FTIR spectrometers, such as portable and low-resolution FTIR instruments with a potentially higher spatial coverage. The spectral AOD dependence for the seven FTIR micro-windows have been also examined, observing a spectrally flat AOD behaviour for mineral dust particles (the typical atmospheric aerosols presented at IZO). A mean AE value of 0.53 ± 0.08 for pure mineral dust in the 1020–2314 nm spectral range was retrieved in this paper. A subsequent cross-validation with the MOPSMAP (Modeled optical properties of ensembles of aerosol particles) package has ensured the reliability of the FTIR dataset, with AE values between 0.36 to 0.60 for a typical mineral dust content at IZO of 100 cm$^{−3}$ and water-soluble particle (WASO) content ranging from 600 to 6000 cm$^{−3}$. The new database generated in this study is believed to be the first long-term time series (1-year) of aerosol properties generated consistently in the NIR and SWIR ranges from ground-based FTIR spectrometry. As a consequence, the results presented here provide a very promising tool for the validation and subsequent improvement of satellite aerosol products as well as enhance the sensitivity to large particles of the existing databases, required to improve the estimation of the aerosols’ radiative effect on climate

A plasmonic route towards the energy scaling of on-chip integrated all-photonic phase-change memories

This is the author accepted manuscript.Phase-change photonic memory devices, conventionally implemented as a thin layer of phase-change material deposited on the top of an integrated Si or SiN waveguide, have the flexibility to be applied in a widely diverse context, as a pure memory device, a logic gate, an arithmetic processing unit and for biologically inspired computing. In all such applications increasing the speed, and reducing the power consumption, of the phase-switching process is most desirable. In this work, therefore, we investigate, via simulation, a novel integrated photonic device architecture that exploits plasmonic effects to enhance the light-matter interaction. Our device comprises a dimer nanoantenna fabricated on top of a SiN waveguide and with a phase-change material deposited into the gap between the two nanoantenna halves. We observed very considerably increased device speeds and reduced energy requirements, of up to two orders of magnitude, when compared to the conventional structure.Engineering and Physical Sciences Research Council (EPSRC

Comparison between measurements and model simulations of solar radiation at a high altitude site: case studies for the Izaña BSRN Station [Póster]

Póster presentado en: International Radiation Symposium, celebrado del 6 al 10 de agosto de 2012 en Berlín, Alemania.Financial supports from the Spanish MICIIN for projects CGL2009-09740, CGL2011-23413 and CGL2010-09480E, CGL2011-13085-E are gratefully acknowledged. We authors to acknowledge the AERONET-PHOTONS-RIMA networks (http://aeronet.gsfc.nasa.gov) and the LibRadtran model (http://www.libradtran.org)

Low X-Ray Luminosity Galaxy Clusters: Main goals, sample selection, photometric and spectroscopic observations

We present the study of nineteen low X-ray luminosity galaxy clusters (L$_X \sim$ 0.5--45 $\times$ $10^{43}$ erg s$^{-1}$), selected from the ROSAT Position Sensitive Proportional Counters (PSPC) Pointed Observations (Vikhlinin et al. 1998) and the revised version of Mullis et al. (2003) in the redshift range of 0.16 to 0.7. This is the introductory paper of a series presenting the sample selection, photometric and spectroscopic observations and data reduction. Photometric data in different passbands were taken for eight galaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observatory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only four galaxy clusters using Gemini telescopes. With the photometry, the galaxies were defined based on the star-galaxy separation taking into account photometric parameters. For each galaxy cluster, the catalogues contain the PSF and aperture magnitudes of galaxies within the 90\% completeness limit. They are used together with structural parameters to study the galaxy morphology and to estimate photometric redshifts. With the spectroscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km~s$^{-1}$ for [VMF98]022 to 775 km~s$^{-1}$ for [VMF98]097 with signs of substructure. Cluster membership has been extensively discussed taking into account spectroscopic and photometric redshift estimates. In this sense, members are the galaxies within a projected radius of 0.75 Mpc from the X-ray mission peak and with cluster centric velocities smaller than the cluster velocity dispersion or 6000 km~s$^{-1}$, respectively. These results will be used in forthcoming papers to study, among the main topics, the red cluster sequence, blue cloud and green populations; the galaxy luminosity function and cluster dynamics.Comment: 13 pages, 6 tables, 9 figures. Uses emulateapj. Accepted for publication in The Astronomical Journal. Some formatting errors fixe

New textures of chocolate are formed by polymorphic crystallization and template effects: velvet chocolate

We report new types of chocolate textures with a soft mouth-feel (velvet effect) formed by controlling the crystallization and polymorphic transformation of cocoa butter (CB) with thermal treatment and template effects. A quick spray of molten chocolate liquor on chilled substrates (normally formed chocolate or metal) caused the crystallization of metastable forms of CB, which transformed to a stable form during subsequent heating processes. Cryo-scanning electron microscopy and confocal interferometric scanning microscopy were employed to observe the surface structures of the velvet chocolate. We characterized the domain sizes of the βV form for the CB crystals in velvet chocolate, which were much smaller and exhibited a lower melting temperature and softer mouth-feel than those in normally tempered chocolate. Polymorphic crystallization and transformation of CB were monitored in situ by X-ray diffraction by changing the temperatures of the substrates. It was obvious that the velvet effect was induced solely by decreasing the temperature of the substrates below 16 °C, because crystallization of the metastable γI form and subsequent transformation to βV of CB are prerequisites for forming velvet chocolate. The chocolate substrate was much more effective than the metal substrate in forming the velvet chocolate because of the template effect