105 research outputs found
Hausdorff dimension of random limsup sets
We prove bounds for the almost sure value of the Hausdorff dimension of the
limsup set of a sequence of balls in whose centres are
independent, identically distributed random variables. The formulas obtained
involve the rate of decrease of the radii of the balls and multifractal
properties of the measure according to which the balls are distributed, and
generalise formulas that are known to hold for particular classes of measures.Comment: 26 pages, 2 figures; v2: Minor correction
On the Fourier dimension and a modification
We give a sufficient condition for the Fourier dimension of a countable union
of sets to equal the supremum of the Fourier dimensions of the sets in the
union, and show by example that the Fourier dimension is not countably stable
in general. A natural approach to finite stability of the Fourier dimension for
sets would be to try to prove that the Fourier dimension for measures is
finitely stable, but we give an example showing that it is not in general. We
also describe some situations where the Fourier dimension for measures is
stable or is stable for all but one value of some parameter. Finally we propose
a way of modifying the definition of the Fourier dimension so that it becomes
countably stable, and show that a measure has modified Fourier dimension
greater than or equal to if and only if it annihilates all sets with
modified Fourier dimension less than .Comment: v2: Added some remarks in the introduction and after Example 6. v3:
Revised the introduction, strengthened Lemma 6, added Proposition 5 and
Example 8. To appear in Journal of Fractal Geometr
Optimering av tanninextraktion
Varje Är produceras cirka 1 miljon ton slam i de svenska reningsverken. I slammet ackumuleras oönskade metaller och organiska Àmnen. För att avvattna och skilja slammet frÄn avloppsvattnet och effektivisera transporten till deponi eller Äkermark som gödsel anvÀnds ett flocknings-/koaguleringsmedel. Vanligtvis anvÀnds den syntetiska polymeren polyakrylamid vid slamflockning. Polymeren bryts dock ner lÄngsamt eller inte alls i naturen vilket kan bidra till en ackumulation i marken. Tanniner extraherat frÄn bark har visat liknande egenskaper, kommersiella flockningsprodukter finns men tillverkas utomlands och dÄ frÀmst frÄn akacia. Intresse finns att utvÀrdera möjligheterna att extrahera tanniner frÄn, inhemska trÀdslag för senare anvÀndning mot avloppsslam och som retentionsmedel inom massaindustrin inom Sverige.
DÄ varje trÀdslag Àr unikt krÀvs olika förhÄllanden för optimal extraktion, dÀrför behövs en metod som utvÀrderar vilka faktorer som pÄverkar tanninutfallet pÄ inhemska trÀdslag. Syftet med detta examensarbete blir dÀrav att kontrollera vilken inverkan de tre faktorerna temperatur, bark/liter lösningsmedel (TS-halt) och fraktionsstorlek har pÄ extraktionsutfallet pÄ trÀdslaget tall (Pinus sylvestris). Tanninerna extraherades genom att barken, under omrörning, fick ligga i en 8-procentig natriumkarbonatlösning. De tre faktorernas vÀrden varierade mellan försöken och prover togs efter 4, 8, 16, 32 och 64 minuter. MÀngden fenoler kontrollerades med hjÀlp av en fotospektrometer.
Resultatet visade att alla tre faktorerna hade en signifikant inverkan pĂ„ extraktionsutfallet. Ăkad temperatur och bark/liter lösningsmedel hade positiv korrelation med extraktionsutbytet medan ökad fraktionsstorlek visade negativ korrelation. Under studien uppnĂ„ddes inget optimalt förhĂ„llande för maximerat extraktionsutfall men det visade att framgĂ„ngsrik extraktion av tanniner frĂ„n inhemskt trĂ€dslag Ă€r möjlig.sludge accumulates unwanted metals and organic substances. In order to dewater and separate the sludge from the waste-water and stream-line the transport to landfills or farmland as fertilizer, a flocculation/coagulation agent is used. The most commonly used product in sludge flocculation is the synthetic polymer polyacrylamide. The polymer breaks down slowly or not at all in nature, which can contribute to an accumulation in the soil. Tannins extracted from the bark have similar properties, commercial flocking agents exists but are manufactured abroad, mainly from the bark of the Acacia tree. There is an interest to evaluate the possibilities of extracting tannins from, native tree species for later use against sludge and retention aids in the paper industry in Sweden. As each species is unique, they require different conditions for optimal extraction, therefore a method is needed that evaluates the factors that influence tannin extraction of native tree species. The purpose of this study is hence to evaluate what the impact of the three factors; temperature, bark/liter of solvent and fraction size, has on extraction outcome for the tree species pine (Pinus sylvestris). The tannins was extracted from the bark into an eight percent sodium carbonate solution while stirring. The values of the three factors varied between the trials and samples were taken after 4, 8, 16, 32 and 64 minutes. The amount of phenols was measured using a spectrophotometer. The results showed that all three factors had a significant impact on the extraction outcome. Increased temperature and bark/liter solvent had a positive correlation with the extraction yield while increased fraction size showed a negative correlation. During the study no optimal ratio for maximized outcome was achieved, but showed that the extraction of tannins from indigenous tree species is promising
Current epigenetic aspects the clinical kidney researcher should embrace
Chronic kidney disease (CKD), affecting 10-12% of the world's adult population, is associated with a considerably elevated risk of serious comorbidities, in particular, premature vascular disease and death. Although a wide spectrum of causative factors has been identified and/or suggested, there is still a large gap of knowledge regarding the underlying mechanisms and the complexity of the CKD phenotype. Epigenetic factors, which calibrate the genetic code, are emerging as important players in the CKD-associated pathophysiology. In this article, we review some of the current knowledge on epigenetic modifications and aspects on their role in the perturbed uraemic milieu, as well as the prospect of applying epigenotype-based diagnostics and preventive and therapeutic tools of clinical relevance to CKD patients. The practical realization of such a paradigm will require that researchers apply a holistic approach, including the full spectrum of the epigenetic landscape as well as the variability between and within tissues in the uraemic milieu
TvÄ höjdtilldelningsmetoder för trÀdhöjder
Detta kandidatarbete avsÄg att utvÀrdera tvÄ metoder för höjdtilldelning av enskilda trÀd och hur dessa pÄverkade kvalitén pÄ skattningar av grundytevÀgd medelhöjd gjord med hjÀlp av laserdata. De metoder som utvÀrderades var Söderbergs funktioner och en ny metod som Riksskogstaxeringen nyligen tagit
fram. Studien skedde i tre delar, först en jÀmförelse mellan de vÀrden för varje provyta som tilldelats enligt Söderbergs funktioner respektive Riksskogstaxeringens
metod, sedan en regressionsanalys av mÀngden vÀrden frÄn respektive metod och laserdata, och slutligen en granskning av regressionsfunktionernas noggrannhet gentemot fÀltinventerade provytor som inte anvÀndes i framtagandet
av funktionerna. För att göra dessa analyser anvÀndes Riksskogstaxeringens provytor, LantmÀteriets laserdata samt provytor tillhandahÄllna av Bergvik Skog.Resultatet visade pÄ att den nya metoden gav systematiskt högre skattningar Àn
Söderbergs funktioner. Skattningar gjorda utifrÄn laserdata baserade pÄ den nya metoden hamnade nÀrmare det fÀltinventerade vÀrdet, jÀmfört med skattningar grundade pÄ Söderbergs funktioner.The aim of this bachelors degree thesis was to analyze how estimations of basal area weighted mean height made with airborne laser scanning (ALS) data is affected by the tree wise height estimation method used for the plots before
regression analysis. The methods compared are Söderbergâs functions and a new method produced by the Swedish National Forest Inventory (NFI). This study was performed in three parts. First an initial comparison between the values
assigned to every plot was made. Then a regression analysis between these values and laser data was completed. Finally an evaluation of estimations made with the computed functions versus third party inventoried values was performed. To make this analysis, data was used that came from the NFI, LantmĂ€terietâs (the Swedish national land survey) national laser scanning, and Bergvik Skog.
The result showed that the new method developed by the NFI systematically produced a higher value than Söderbergâs functions. It was found that the estimates, made with ALS data, based on the new height estimation method
showed better agreement with the evaluation data from Bergvik Skog than the estimates based on Söderbergâs functions
ANALISIS PENERAPAN TOTAL PRODUCTIVE MAINTENANCE (TPM) DI PT CHANDRA ASRI PETROCHEMICAL TBK
PT Chandra Asri Petrochemical Tbk merupakan perusahaan terbesar dan
terintegrasi di Indonesia yang menghasilkan produk biji plastik. Dalam dunia
industri petrokimia, kondisi dan kinerja alat dan mesin menjadi salah satu penentu
pencapaian target produksi yang ditetapkan. Kondisi mesin dan peralatan harus
dijaga agar selalu dalam kondisi prima dan siap digunakan seoptimum mungkin
dengan cara pemeliharaan dan perbaikan (maintenance). Dari hasil laporan data
tahunan yang dimiliki perusahaan diketahui adanya permasalahan yang sering
terjadi di mesin Product Discharge System pada train 2 sehingga sering terjadi
breakdown.
Salah satu metode yang dapat mengetahui pengaruh breakdown terhadap jumlah
produksi yaitu dengan menggunakan metode Overall Equipment Effectiveness
(OEE), di mana breakdown menjadi salah satu indikator yang digunakan dalam
perhitungan OEE yaitu Availability. Dengan perhitungan yang ada, maka akan
didapatkan hasil nilai Overall Equipment Effectiveness dan dilanjutkan dengan
proses analisis six big losses untuk menentukan kerugian mana saja yang paling
berpengaruh.
Hasil dari penelitian yaitu didapatnya hasil rata-rata Overall Equipment
Effectiveness yaitu sebesar 85,4% dengan losses terbesar ditemukan pada
Equipment Failure Losses dengan persentase paling besar yaitu 47,65% dari
keenam losses lainnya. Dari hasil Equipment Failure Losses ini dapat diketahui
bahwa yang mempengaruhi besarnya nilai dari hasil tersebut dikarenakan angka
kerusakan pada valve Product Discharge System yang cukup tinggi serta waktu
untuk setup dan adjustment yang lama. Berdasarkan hasil tersebut serta
konsultasi dengan pihak perusahaan, maka didapatkan beberapa solusi yang
dapat diimplementasikan perusahaan untuk perbaikan ke depannya yang lebih
baik
Alterations in the neuropeptide galanin system in major depressive disorder involve levels of transcripts, methylation, and peptide
Major depressive disorder (MDD) is a substantial burden to
patients, families, and society, but many patients cannot be
treated adequately. Rodent experiments suggest that the
neuropeptide galanin (GAL) and its three G protein-coupled
receptors, GAL1â3, are involved in mood regulation. To explore
the translational potential of these results, we assessed the
transcript levels (by quantitative PCR), DNA methylation status
(by bisulfite pyrosequencing), and GAL peptide by RIA of the GAL
system in postmortem brains from depressed persons who had
committed suicide and controls. Transcripts for all four members
were detected and showed marked regional variations, GAL and
galanin receptor 1 (GALR1) being most abundant. Striking
increases in GAL and GALR3 mRNA levels, especially in the
noradrenergic locus coeruleus and the dorsal raphe nucleus, in
parallel with decreased DNA methylation, were found in both male
and female suicide subjects as compared with controls. In
contrast, GAL and GALR3 transcript levels were decreased, GALR1
was increased, and DNA methylation was increased in the
dorsolateral prefrontal cortex of male suicide subjects,
however, there were no changes in the anterior cingulate cortex.
Thus, GAL and its receptor GALR3 are differentially methylated
and expressed in brains of MDD subjects in a region- and sex-
specific manner. Such an epigenetic modification in GALR3, a
hyperpolarizing receptor, might contribute to the dysregulation
of noradrenergic and serotonergic neurons implicated in the
pathogenesis of MDD. Thus, one may speculate that a GAL3
antagonist could have antidepressant properties by disinhibiting
the firing of these neurons, resulting in increased release of
noradrenaline and serotonin in forebrain areas involved in mood
regulation
- âŠ