| 1. |
- Adalbjörnsson, Stefan Ingi, et al.
(författare)
-
Sparse Localization of Harmonic Audio Sources
- 2016
-
Ingår i: IEEE/ACM Transactions on Audio, Speech, and Language Processing. - 2329-9290. ; 24:1, s. 117-129
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a novel method for estimating the locations of near- and/or far-field harmonic audio sources impinging on an arbitrary, but calibrated, sensor array. Using a joint pitch and location estimation formed in two steps, we first estimate the fundamental frequencies and complex amplitudes under a sinusoidal model assumption, whereafter the location of each source is found by utilizing both the difference in phase and the relative attenuation of the magnitude estimates. As audio recordings often consist of multi-pitch signals exhibiting some degree of reverberation, where both the number of pitches and the source locations are unknown, we propose to use sparse heuristics to avoid the necessity of detailed a priori assumptions on the spectral and spatial model orders. The method’s performance is evaluated using both simulated and measured audio data, with the former showing that the proposed method achieves near-optimal performance, whereas the latter confirms the method’s feasibility when used with real recordings.
|
|
| 2. |
- Andersson, Camilla, et al.
(författare)
-
Achievements and experiences from science–policy interaction in the field of air pollution : Synthesising 20 years of research and outreach,thinking about future needs
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- For 20 years, the Swedish Environmental Protection Agency together with the MISTRA research foundation have funded five air pollution research programmes with focus on producing knowledge that supports policy and emission control in national and international arenas. The research has been multidisciplinary and has included research on emissions, atmospheric transport and transformation processes, human health effects, ecosystem effects, and emission control strategies. Research has also been conducted on the interaction between air pollution and climate change.Over these years, the link between the research programmes and the development of emission control strategies and policies in Sweden, the EU, and the UNECE Air Convention has been of high importance. This report presents how the research programmes have created societal benefits through support for the development of air pollution policies and emission control measures. The report also identifies future research needs to ensure continued progress towards even better air quality for future generations.
|
|
| 3. |
- Arnell, Jenny, et al.
(författare)
-
Impact from policy instruments on use of industrial excess heat
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Increasing resource efficiency and reducing carbon emissions in manufacturing industry are prioritised objectives in both international and domestic policies. At the same time, Swedish industry is struggling to remain competitive in international markets. There is at the same time increasing internal competition for bio-based resources among sectors. Currently there are a number of taxes, restrictions and other policy instruments targeted with the goals to increase the use of renewable energy, reduce greenhouse gas emissions and improve energy efficiency. Excess heat from industry accounts for almost 5 TWh of the delivered heat to district heating in Sweden today but there is a potential for further recovery of excess heat. An increased utilization of industrial excess heat is desirable in terms both of improved energy efficiency and resource efficiency. This project describes the impact from existing policy instrument on one important solution to improve the energy- and resource efficiency of the energy system: the use of industrial excess or residual heat for district heating networks. There are several policy instruments with an impact but only a few that gives benefits for the use of industrial excess heat. The Regulated Access to the district heat implemented in the Swedish policy for district heating, put up guidance regarding under which conditions an industry can demand access, and point out that the cost should be taken by the industry part. The Energy Efficient Directive governs that a complete cost benefit analysis including existing industrial excess heat must be examined when planning a new process or plant. And the market-based support system for renewable electricity production, the electricity certificates. In the case of chemical industries in Stenungsund excess heat could be delivered to the district heating networks in Kungälv and/or Gothenburg. An optimisation in a regional cost minimising model of the energy system in Västra Götaland of Sweden shows the possibilities to deliver heat. In this report the consequence on the used amount of excess heat from electricity certificates are presented. The studied energy system of Västra Götaland will use more excess heat for district heating when there is no or low price on the certificates. This report is only available in English.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Barsoum, Emad, 1979-, et al.
(författare)
-
{alpha}3, a transposable element that promotes host sexual reproduction
- 2010
-
Ingår i: Genes & Development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 24:15, s. 33-44
-
Tidskriftsartikel (refereegranskat)abstract
- Theoretical models predict that selfish DNA elements require host sex to persist in a population. Therefore, a transposon that induces sex would strongly favor its own spread. We demonstrate that a protein homologous to transposases, called alpha3, was essential for mating type switch in Kluyveromyces lactis. Mutational analysis showed that amino acids conserved among transposases were essential for its function. During switching, sequences in the 5' and 3' flanking regions of the alpha3 gene were joined, forming a DNA circle, showing that alpha3 mobilized from the genome. The sequences encompassing the alpha3 gene circle junctions in the mating type alpha (MATalpha) locus were essential for switching from MATalpha to MATa, suggesting that alpha3 mobilization was a coupled event. Switching also required a DNA-binding protein, Mating type switch 1 (Mts1), whose binding sites in MATalpha were important. Expression of Mts1 was repressed in MATa/MATalpha diploids and by nutrients, limiting switching to haploids in low-nutrient conditions. A hairpin-capped DNA double-strand break (DSB) was observed in the MATa locus in mre11 mutant strains, indicating that mating type switch was induced by MAT-specific DSBs. This study provides empirical evidence for selfish DNA promoting host sexual reproduction by mediating mating type switch.
|
|
| 7. |
- Barsoum, Emad, 1979-
(författare)
-
Mating type switching and transcriptional silencing in Kluyveromyces lactis
- 2010
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To explore the similarities and differences of regulatory circuits among budding yeasts, we characterized the role of unscheduled meiotic gene expression 6 (UME6) and a novel mating type switching pathway in Kluyveromyces lactis. We found that Ume6 was required for transcriptional silencing of the cryptic mating-type loci HMLα and HMRa. Ume6 acted directly at these loci by binding to the cis-regulatory silencers. Ume6 also served as a block to polyploidy and was required for repression of three meiotic genes, independently of the Rpd3 and Sin3 corepressors. Mating type switching from MATα to MATa required the α3 protein. The α3 protein was similar to transposases of the mutator like elements (MULEs). Mutational analysis showed that the DDE-motif in α3, which is conserved in MULEs was necessary for switching. During switching α3 mobilizes from the genome in the form of a DNA circle. The sequences encompassing the α3 gene circle junctions in the MATα locus were essential for switching from MATα to MATa. Switching also required a DNA binding protein, Mating type switch 1 (Mts1), whose binding sites in MATα were important. Expression of Mts1 was repressed in MATa/MATα diploids and by nutrients, limiting switching to haploids in low nutrient conditions. In a genetic selection for strains with increased switching rates we found a mutation in the RAS1 gene. By measuring the levels of the MTS1 mRNA and switching rates in ras1, pde2 and msn2 mutant strains we show that mating type switching in K. lactis was regulated by the RAS/cAMP pathway and the transcription factor Msn2. ras1 mutants contained 20-fold higher levels of MTS1 mRNA compared to wild type whereas pde2 and msn2 expressed less MTS1 mRNA and had decreased switching rates. Furthermore we found that MTS1 contained several potential Msn2 binding sites upstream of its ORF. We suggest that these observations explain the nutrient regulation of switching.
|
|
| 8. |
- Barsoum, E., et al.
(författare)
-
RAS/Cyclic AMP and Transcription Factor Msn2 Regulate Mating and Mating-Type Switching in the Yeast Kluyveromyces lactis
- 2011
-
Ingår i: Eukaryotic Cell. - 1535-9778 .- 1535-9786. ; 10:11, s. 1545-1552
-
Tidskriftsartikel (refereegranskat)abstract
- In response to harsh environmental conditions, ascomycetes produce stress-resistant spores to promote survival. As sporulation requires a diploid DNA content, species with a haploid lifestyle, such as Kluyveromyces lactis, first induce mating in response to stress. In K. lactis, mating and mating-type switching are induced by the DNA-binding protein Mts1. Mts1 expression is known to be upregulated by nutrient limitation, but the mechanism is unknown. We show that a ras2 mutation results in a hyperswitching phenotype. In contrast, strains lacking the phosphodiesterase Pde2 had lower switching rates compared to that of the wild type (WT). As Ras2 promotes cyclic AMP (cAMP) production and Pde2 degrades cAMP, these data suggest that low cAMP levels induce switching. Because the MTS1 regulatory region contains several Msn2 binding sites and Msn2 is a transcription factor that is activated by low cAMP levels, we investigated if Msn2 regulates MTS1 transcription. Consistently with this idea, an msn2 mutant strain displayed lower switching rates than the WT strain. The transcription of MTS1 is highly induced in the ras2 mutant strain. In contrast, an msn2 ras2 double mutant strain displays WT levels of the MTS1 transcript, showing that Msn2 is a critical inducer of MTS1 transcription. Strains lacking Msn2 and Pde2 also exhibit mating defects that can be complemented by the ectopic expression of Mts1. Finally, we show that MTS1 is subjected to negative autoregulation, presumably adding robustness to the mating and switching responses. We suggest a model in which Ras2/cAMP/Msn2 mediates the stress-induced mating and mating-type switching responses in K. lactis.
|
|
| 9. |
- Barsoum, Emad, 1979-, et al.
(författare)
-
Regulation of mating type switching in Kluyveromyces lactis by the RAS/cAMP pathway and the transcription factor Msn2
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We explored the regulation of mating type switching in Kluyveromyces lactis. Using an assay dependent on loss of a URA3 gene inserted into the MATa locus, we determined that the switching rate of a wild type strain grown in rich media was ~6X10-4 events/generation. In a genetic selection for identifying strains with increased switching rates, we found a strain with an insertion in the K. lactis RAS1 gene, encoding a small GTPase with a central role in growth regulation. Compromised Ras1 function leads to a lower cAMP level suggesting a role for cAMP in promoting switching. Consistent with this idea, a strain lacking the PDE2 gene, which encodes an enzyme that degrades cAMP, resulted in decreased switching rates. To explore how cAMP regulated switching, we investigated the transcription of the MTS1 gene, encoding an inducer of switching. The ras1 mutant strain contained 20-fold higher levels of the MTS1 mRNA compared to wild type, but in the pde2 mutant strain MTS1 transcription was repressed 5-fold. In addition, strains lacking the MSN2 gene, which encodes a transcription factor that binds the stress response element (STRE), expressed less MTS1 mRNA and had decreased switching rates. We suggest a model in which nutrient limitation induces switching through cAMP and Msn2-dependent transcriptional induction of the MTS1 gene.
|
|
| 10. |
- Barsoum, Emad, 1979-, et al.
(författare)
-
Ume6 is required for the MATa/MATα cellular identity and transcriptional silencing in Kluyveromyces lactis
- 2010
-
Ingår i: Genetics. - : The Genetics Society of America. - 0016-6731 .- 1943-2631. ; 184:4, s. 999-1011
-
Tidskriftsartikel (refereegranskat)abstract
- To explore the similarities and differences of regulatory circuits among budding yeasts, we characterized the role of the unscheduled meiotic gene expression 6 (UME6) gene in Kluyveromyces lactis. We found that Ume6 was required for transcriptional silencing of the cryptic mating-type loci HMLα and HMRa. Chromatin immunoprecipitation (ChIP) suggested that Ume6 acted directly by binding the cis-regulatory silencers of these loci. Unexpectedly, a MATa ume6 strain was mating proficient, whereas a MATα ume6 strain was sterile. This observation was explained by the fact that ume6 derepressed HMLα2 only weakly, but derepressed HMRa1 strongly. Consistently, two a/α-repressed genes (MTS1 and STE4) were repressed in the MATα ume6 strain, but were expressed in the MATa ume6 strain. Surprisingly, ume6 partially suppressed the mating defect of a MATa sir2 strain. MTS1 and STE4 were repressed in the MATa sir2 ume6 double-mutant strain, indicating that the suppression acted downstream of the a1/α2-repressor. We show that both STE12 and the MATa2/HMRa2 genes were overexpressed in the MATa sir2 ume6 strain. Consistent with the idea that this deregulation suppressed the mating defect, ectopic overexpression of Ste12 and a2 in a MATa sir2 strain resulted in efficient mating. In addition, Ume6 served as a block to polyploidy, since ume6/ume6 diploids mated as pseudo a-strains. Finally, Ume6 was required for repression of three meiotic genes, independently of the Rpd3 and Sin3 corepressors.
|
|
