196,288 research outputs found
The hair in childhood and old age
No full textMore than 20 syndromes, most congenital, have hypertrichosis as a feature. An excessive growth of non-androgen-dependent hair has been reported in association with many acquired diseases and medications, some of which, as cyclosporine, can be administered also in children. Even though primary hypertrichosis is benign in most cases, it may result in cosmetic disfigurement and psychosocial trauma; a pediatric assessment is necessary to rule out associated diseases. Lanugo hair can occur in otherwise healthy individuals but can be associated with polymyositis and neoplasms. Hirsutism can be idiopathic, but often can be associated with an adrenal or ovarian cause. Thus all women with hirsutism require careful evaluation. More, growing evidence has linked hyperandrogenism to increased risk of cardiovascular disease, genital tract neoplasms, and non-insulin-dependent diabetes mellitus. An application from the study of hairs comes from oligoelements. A recent study investigating the zinc status of eighty newborn babies with neural tube defects and their mothers compared with controls found a positive association between this defects and decreased hair zinc levels. As far it concerns the color of hairs our group has demonstrated that heterochromia of the scalp hair can be a sign of pigmentary mosaicism even without underlying malformations. The present elucidation of pathogenesis of androgenetic alopecia has lead to second generation steroidal 5α reductase inhibitors, such as G-198745 (a combined type 1 and type 2, 5α reductase blocker), W09704002, Turosteride, Mk-963, MK-434, Episteride, and MK-386. A variety of non-steroidal inhibitors such as zinc and saw palmetto are also under investigation. The possibility of gene therapy for androgenetic alopecia has been advanced in animal by the development of a cream capable to deliver DNA to hair follicles. Finally, the study of the stem cells of the hair follicle will give us new possibilities of treatment
Ionosphere compensation and stepped frequency processing in the MARSIS experiment
No full textThis paper is addressed to the improvement of the range resolution of MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) by means of a modified version of the stepped frequency processing algorithm. MARSIS is a low frequency, pulse-limited radar sounder and altimeter selected by ESA as a payload of the Mars Express mission. The ionosphere affects MARSIS operation in terms of phase distortion, attenuation and Faraday rotation. The ionosphere fine compensation is obtained according to the uniform model, allowing, with the correctly compensated data, the production of MARSIS images at higher resolution. In this way it is possible to detect hidden interfaces never seen before due to MARSIS coarse vertical resolution. © 2011 IEEE
Shallow Radar (SHARAD) investigations over Sinus Meridiani
No full textMars equatorial region Sinus Meridiani has been investigated by the Thermal Emission Spectrometer (TES) onboard the Mars Global Surveyor (MGS) revealing the presence of gray hematite. Laboratory measurements on magnetic minerals including gray hematite have been performed afterwards suggesting that the Shallow Radar (SHARAD) instrument onboard the Mars Reconnaissance Orbiter (MRO) should be capable to reveal the reflectivity contrast, the influence on the penetration depth and the temperature dependence effect on the received echoes. The proposed wok suggests a possible study aimed to evaluate such considerations including both theoretical models as well as experimental data analysis
Resveratrol derivatives and their role as potassium channels modulators
No full textA series of stilbenoid analogues of resveratrol (trans-3,4',5-trihydroxystilbene) with a stilbenic or a bibenzylic skeleton have been prepared by partial synthesis from resveratrol and dihydroresveratrol. The synthesized compounds have been evaluated for their ability to modulate voltage-gated channels
Weighting network influence on the geometric term correction in MARSIS data inversion
No full textMars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) is a low frequency, pulse-limited radar sounder and altimeter selected by ESA as a payload of the Mars Express mission. This work retraces the processing that leads to the extraction of parameters needed to perform the data inversion pointing out an effect caused by the weighting network application in presence of volume scattering that could jeopardize the backscattering-related geometry interpretation on a specific set of data
Martian magnetic minerals signature detection by Shallow Radar (SHARAD)
No full textNear-global thermal infrared mapping by the Thermal Emission Spectrometer (TES) on Mars Global Surveyor
has revealed unique deposits of crystalline gray hematite (a-Fe2O3) exposed at the Martian surface in the Sinus
Meridiani region. The material is an in-place, rock stratigraphic sedimentary unit characterized by smooth, friable
layers composed primarily of basaltic sediments with 0-20% crystalline gray hematite.
Shallow Radar (SHARAD) is a ground penetrating radar (GPR) provided by the Italian Space Agency
(ASI) and selected by NASA for the Mars Reconnaissance Orbiter (MRO) mission. The goal of this nadir-looking
altimeter with synthetic aperture capabilities is to investigate the surface and subsurface of Mars providing data
about the crustal composition of the planet. The sounder operates using a 20 MHz carrier and a bandwidth of
10 MHz (from 15 to 25 MHz) to achieve a theoretical vertical resolution of 15 m in free space, maintaining an
acceptable penetration capability of approximately 1500 m. Performance of the instrument can however be highly
dependent on the operating environment and in particular on the reflectivity of the surface and the subsurface, on
the effect of the ionosphere and on the level of clutter echoes, which in turn depend on the surface topography.
Laboratory measurements of electrical and magnetic properties of grey hematite at Mars ambient temperatures
in the ground penetrating radar frequency range have produced surprisingly strong dielectric relaxations
as well as the expected magnetic properties. At the average Mars surface temperature of 213 K hematite has a
strong dielectric relaxation near 15 MHz which is strongly temperature dependent. Between day and night this
relaxation will move through the frequency range of SHARAD that may be capable of identifying the temperature
dependence.
Several works regarding the effect that magnetic materials should have on the signal transmitted by ground
penetrating radars like SHARAD have been proposed in the past. Since a vast data set has been acquired by the
sensor over Sinus Meridiani the present study aims to validate previous works underlining the limitation that
surface geometry induces on the data analysis
Range compression optimization for subsurface investigation in the MARSIS experiment
No full textThis work deals with the range compression applied to MARSIS (Mars Radar for Subsurface and Ionosphere Sounding) data proposing a new approach to improve the S/N after matched filtering for both surface and subsurface responses. It will be also illustrated how the geometric term correction can be performed on a particular class of data previously not correctable according to surface/subsurface theoretical models. Finally, it will be demonstrated how a better estimation of the volume scattering can be obtained. © 2012 IEEE
Doppler analysis for data inversion and image processing in the MARSIS experiment
No full textThis paper is addressed to MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) signal analysis. The effect of tilted layers, detected within different Doppler filters, is taken into account in order to improve the quality and the quantity of the data set needed to perform the data inversion, that is the estimation of the dielectric constant of the materials composing the different detected interfaces. © 2011 IEEE
Media che cambiano, parole che restano
No full textIl libro si propone di tracciare lo status quaestionis dei nuovi fenomeni che si stanno manifestando nell'universo dei media e della comunicazione. La realtà dei media è in costante trasformazione. Spesso emergono nuove piattaforme o nuove tendenze che non si fa in tempo a metabolizzare e contestualizzare prima che si esauriscano e smarriscano la propria energia propulsiva. Quello che occorre è uno sguardo, insieme descrittivo e riflessivo, che si soffermi ad analizzare ciascuna di queste nuove emergenze tentando di valutarne attentamente le conseguenze sociali e culturali, al di là di mode effimere o di interessi di corto respiro. Più che un lessico sui media, questo libro intende costruire un repertorio di temi per leggere il presente attraverso i fenomeni che interessano la comunicazione: quali le dinamiche della contemporaneità, le linee di tendenza che costituiranno la nuova agenda setting di chi riflette e si interroga sul destino della società e delle correnti che alimentano i new media? Si tratta di un libro collettaneo, scritto da studiosi che si sono occupati di temi rilevanti per l'interpretazione del mondo-media: per ciascun concetto viene esplicitato da quando se ne parla, in quali termini, quali sono gli elementi di problematizzazione nel dibattito attuale, quali le prospettive e le implicazioni sul piano dei mutamenti socio-culturali. E' un libro agile, uno strumento utile per fare il punto sulle nuove tendenze che emergono nel panorama dei media oggi, ma anche uno stimolo prezioso per contribuire ad allargare lo spettro dei fenomeni oggetto di studio dei “comunicazionisti”, nella convinzione che essi possano dire molto della società in cui viviamo a condizione di abbandonare la riserva protetta dello specialismo disciplinare. Un libro sulla comunicazione, certo, ma anche al di là della comunicazione, ovvero al di fuori della provincia finita in cui i media studies stanno negli ultimi tempi rischiando di arroccarsi con l'effetto di sbiadire la loro intrinseca vocazione ad interpretare il mondo contemporaneo.The book aims to track the status questionis of the new phenomena that are occurring in the world of media and communication. The reality of the media is in constant transformation. Often emerging new platforms or new trends that you do not have time to metabolize and contextualize before they sell out and stray from its kinetic energy. What is needed is a look, both descriptive and reflective, that is to stop analyzing each of these new emergencies trying to assess carefully the social and cultural consequences, beyond the passing fads of interests or short respiro.Più that a lexicon on media, this book intends to build a repertoire of themes to read this through the phenomena that affect the communication such as the dynamics of the contemporary, trend lines that will form the new agenda setting and reflects who wonders about the fate of the company and currents that feed the new media? It is a book of collected, written by scholars who have dealt with issues relevant to the interpretation of the world-media: for each concept is explained by when they are spoken, in what terms, what are the elements of problematization in the current debate , what are the prospects and implications of socio-cultural changes. It 'sa book agile, a useful tool to take stock of the new trends that emerge in the media landscape today, but also a valuable stimulus to help widen the spectrum of the phenomena under study of "comunicazionisti" in the belief that they can say a lot about the society we live in a condition to leave the protected reserve of disciplinary specialism. A book on communication, of course, but also beyond the communication, ie outside the province ended up in the media in recent times studies are threatening to fade away with the fading effect of their intrinsic vocation to interpret the contemporary world
Heterochromia of the scalp hair: a result of pigmentary mosaicism?
No full textFive patients who presented stable bands of hair of a different color with respect to the surrounding hair are reported. In 4 patients this was an isolated finding. One patient also had diffuse linear skin hypopigmentation and other abnormalities. We hypothesize that these 5 cases represent a distinct type of hair heterochromia, possibly because of somatic mosaicism for genes affecting pigmentation
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