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An affine iterated function system is a finite collection of affine invertible contractions and the invariant set associated to the mappings is called self-affine. In 1988, Falconer proved that, for given matrices, the Hausdorff dimension of the self-affine set is the affinity dimension for Lebesgue almost every translation vectors. Similar statement was proven by Jordan, Pollicott, and Simon in 2007 for the dimension of self-affine measures. In this article, we have an orthogonal approach. We introduce a class of self-affine systems in which, given translation vectors, we get the same results for Lebesgue almost all matrices. The proofs rely on Ledrappier-Young theory that was recently verified for affine iterated function systems by Bárány and Käenmäki, and a new transversality condition, and in particular they do not depend on properties of the Furstenberg measure. This allows our results to hold for self-affine sets and measures in any Euclidean space.
Korkeat rauta- ja mangaanipitoisuudet talousvetenä käytettävissä pohjavesissä aiheuttavat ongelmia maailmanlaajuisesti. Pohjavedenottamon perustamisvaiheessa suoritettavan koepumppauksen avulla pyritään selvittämään ottamokaivosta saatavissa olevan veden laatu ja määrä sekä vedenoton ympäristövaikutukset. Joissain kaivoissa koepumppauksen vedenlaatu ei kuitenkaan vastaa ottamon käytön aikaista laatua. Rauta- ja mangaanipitoisuuksiin vaikuttavat muun muassa pohjaveden happipitoisuus, orgaanisen aineen määrä, sameus sekä pohjavesiesiintymää ympäröivien alueiden geologia. Tutkimuksen tärkeimpänä tavoitteena oli selvittää, voidaanko koepumppauksen vedenlaadun perusteella arvioida luotettavasti ottamon käytön aikaista vedenlaatua ja mitkä tekijät aiheuttavat ottamoiden käytön aikana kohonneet rauta- ja mangaanipitoisuudet. Tutkimuksessa kuvattiin myös yleisesti suomalaisten pohjavedenottamoiden vedenlaatua ja koepumppauksen aikaisia muutoksia laadussa. Lisäksi tarkasteltiin rauta- ja mangaanipitoisuuksien alueellista jakautumista Suomessa. Vuosina 2004 – 2013 vesilain mukaisen luvan saaneista pohjavedenottamoista valittiin tutkimuksen tarkasteluun 67 ottamokaivoa. Tutkimuksen ulkopuolelle jätettiin tekopohjavesilaitokset, ottamokapasiteetin lisäykset ja rantaimeytyslaitokset. Ottamokaivoista tarkasteltiin koepumppauksen kestoa, näytemääriä ja vedenlaatua koepumppauksen ja ottamoiden käytön aikana. Ottamot jaettiin luokkiin eri kriteerien mukaan ja tutkittiin näiden luokkien eroja vedenlaadussa tilastollisen Wilcoxon sijaluku summa -testin avulla. Työssä keskityttiin myös kerätyn aineiston kuvaamiseen. Tutkimuksessa havaittiin happipitoisuuksien olevan matalampia koepumppauksen aikana ottamokaivoissa, joissa raudan tai mangaanin suositusraja ylittyi käytön aikana matalista koepumppauksen pitoisuuksista huolimatta. Keskimääräistä korkeampien koepumppauksen aikaisten CODMn-arvojen havaittiin myös lisäävän korkeiden rauta- ja mangaanipitoisuuksien määrää ottamokaivojen käytön aikaisissa näytteissä. Tarkastelluissa ottamokaivoissa vedenlaatu oli kuitenkin keskimäärin hyvää. Vedenlaadun muutokset koepumppauksessa olivat pieniä ja koepumppauksen tulokset vastasivat käytönaikaista vedenlaatua suurimmassa osassa ottamokaivoista.
We report the development of superluminescent diodes (SLDs) emitting mW-level output power in a broad spectrum centered at a wavelength of 2.55 μm. The emitting structure consists of two compressively strained GaInAsSb/GaSb-quantum wells placed within a lattice-matched AlGaAsSb waveguide. An average output power of more than 3 mW and a peak power of 38 mW are demonstrated at room temperature under pulsed operation. A cavity suppression element is used to prevent lasing at high current injection allowing emission in a broad spectrum with a full width at half maximum (FWHM) of 124 nm. The measured far-field of the SLD confirms a good beam quality at different currents. These devices open further development possibilities in the field of spectroscopy, enabling, for example, detection of complex molecules and mixtures of gases that manifest a complex absorption spectrum over a broad spectral range.
Background Individually submitted prostatic needle biopsies are recommended by most guidelines because of their potential advantage in terms of core quality. However, unspecified bilateral biopsies are commonly submitted in many centers. The length of the core is the key quality indicator of prostate biopsies. Because there are few recent publications comparing the quality of 12 site-designated biopsies versus pooled biopsies, we compared the lengths of the biopsies obtained by both methods. Methods The material was obtained from 471 consecutive subjects who underwent prostatic needle biopsy in the Tampere University Hospital district between January and June 2013. Biopsies from 344 subjects fulfilled the inclusion criteria. The total number of cores obtained was 4047. The core lengths were measured on microscope slides. Extraprostatic tissue was subtracted from the core length. Results The aggregate lengths observed were 129.5 ± 21.8 mm (mean ± SD) for site-designated cores and 136.9 ± 26.4 mm for pooled cores (p = 0.09). The length of the core was 10.8 ± 1.8 mm for site-designated cores and 11.4 ± 2.2 mm for pooled cores (p = 0.87). The median length for pooled cores was 11 mm (range 5 mm – 18 mm). For individual site-designated cores, the median length was 11 mm (range 7 mm −15 mm). The core length was not correlated with the number of cores embedded into one paraffin block (r = 0.015). There was no significant difference in cancer detection rate (p = 0.62). Conclusions Our results suggest that unspecified bilateral biopsies do not automatically lead to reduced core length. We conclude that carefully embedded multiple (three to nine) cores per block may yield cores of equal quality in a more cost-efficient way and that current guidelines favoring individually submitted cores may be too strict.
Several passivation techniques are developed and compared in terms of their ability to preserve the optical properties of close-to-surface InAs/GaAs quantum dots (QDs). In particular, the influence of N-passivation by hydrazine chemical treatment, N-passivation by hydrazine followed by atomic layer deposition (ALD) of AlOx and use of AlNx deposited by plasma-enhanced ALD are reported. The effectiveness of the passivation is benchmarked by measuring the emission linewidths and decay rates of photo-carriers for the near-surface QDs. All three passivation mechanisms resulted in reducing the oxidation of Ga and As atoms at the GaAs surface and consequently in enhancing the room-temperature photoluminescence (PL) intensity. However, long-term stability of the passivation effect is exhibited only by the hydrazine + AlOx process and more significantly by the AlNx method. Moreover, in contrast to the results obtained from hydrazine-based methods, the AlNx passivation strongly reduces the spectral diffusion of the QD exciton lines caused by charge fluctuations at the GaAs surface. The AlNx passivation is found to reduce the surface recombination velocity by three orders of magnitude (corresponding to an increase of room-temperature PL signal by ∼1030 times). The reduction of surface recombination velocity is demonstrated on surface-sensitive GaAs (100) and the passivating effect is stable for more than one year. This effective method of passivation, coupled with its stability in time, is extremely promising for practical device applications such as quantum light sources based on InAs/GaAs QDs positioned in small-volume photonic cavities and hence in the proximity of GaAs-air interface.