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| 11. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 12. |
- Fujita, S., et al.
(författare)
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Spatial and temporal variability of snow accumulation rate on the East Antarctic ice divide between Dome Fuji and EPICA DML
- 2011
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 5:4, s. 1057-1081
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Tidskriftsartikel (refereegranskat)abstract
- To better understand the spatio-temporal variability of the glaciological environment in Dronning Maud Land (DML), East Antarctica, a 2800-km-long Japanese-Swedish traverse was carried out. The route includes ice divides between two ice-coring sites at Dome Fuji and EPICA DML. We determined the surface mass balance (SMB) averaged over various time scales in the late Holocene based on studies of snow pits and firn cores, in addition to radar data. We find that the large-scale distribution of the SMB depends on the surface elevation and continentality, and that the SMB differs between the windward and leeward sides of ice divides for strong-wind events. We suggest that the SMB is highly influenced by interactions between the large-scale surface topography of ice divides and the wind field of strong-wind events that are often associated with high-precipitation events. Local variations in the SMB are governed by the local surface topography, which is influenced by the bedrock topography. In the eastern part of DML, the accumulation rate in the second half of the 20th century is found to be higher by similar to 15% than averages over longer periods of 722 a or 7.9 ka before AD 2008. A similar increasing trend has been reported for many inland plateau sites in Antarctica with the exception of several sites on the leeward side of the ice divides.
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| 13. |
- Abramowski, A., et al.
(författare)
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Revisiting the Westerlund 2 field with the HESS telescope array
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 525, s. A46-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. Previous observations with the HESS telescope array revealed the existence of extended very-high-energy (VHE; E > 100 GeV) gamma-ray emission, HESS J1023-575, coincident with the young stellar cluster Westerlund 2. At the time of discovery, the origin of the observed emission was not unambiguously identified, and follow-up observations have been performed to further investigate the nature of this gamma-ray source. Methods. The Carina region towards the open cluster Westerlund 2 has been re-observed, increasing the total exposure to 45.9 h. The combined dataset includes 33 h of new data and now permits a search for energy-dependent morphology and detailed spectroscopy. Results. A new, hard spectrum VHE gamma-ray source, HESS J1026-582, was discovered with a statistical significance of 7 sigma. It is positionally coincident with the Fermi LAT pulsar PSRJ1028-5819. The positional coincidence and radio/gamma-ray characteristics of the LAT pulsar favors a scenario where the TeV emission originates from a pulsar wind nebula. The nature of HESS J1023-575 is discussed in light of the deep HESS observations and recent multi-wavelength discoveries, including the Fermi LAT pulsar PSRJ1022-5746 and giant molecular clouds in the region. Despite the improved VHE dataset, a clear identification of the object responsible for the VHE emission from HESS J1023-575 is not yet possible, and contribution from the nearby high-energy pulsar and/or the open cluster remains a possibility.
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| 14. |
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| 15. |
- Hu, W., et al.
(författare)
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Electron transport in self-assembled polymer molecular junctions
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 96:2, s. 027801-
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Tidskriftsartikel (refereegranskat)abstract
- A molecular junction of a poly(p-phenyleneethynylene)s derivative with thioacetate end groups (TA-PPE) was fabricated by self-assembling. Nanogap electrodes made by electroplating technique was used to couple thiol end groups of TA-PPE molecules. Room temperature current-voltage characteristics of the molecular junction exhibited highly periodic, repeatable, and identical stepwise features. First-principles calculations suggest that one possibility for the equidistant step is due to the opening of different conducting channels that corresponds to the unoccupied molecular orbitals of the polymer in the junction. It is interesting to see that an 18 nm long polymer is of quantized electronic structures and behaves like a quantum transport device.
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| 16. |
- Luis, R. S., et al.
(författare)
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Demonstration of a 1 Pb/s spatial channel network node
- 2019
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Ingår i: IET Conference Publications. - : Institution of Engineering and Technology.
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Konferensbidrag (refereegranskat)abstract
- We experimentally demonstrate a petabit-class hierarchical SDM switching node with granularity from 10 Tb/s to 1 Pb/s. We address spatial bypassing network scenarios, optical channel grooming, spatial multiplex section protection switching, and optical channels using coupled and uncoupled spatial channels.
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| 17. |
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| 18. |
- Thinh, N. Q., et al.
(författare)
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Identification of Ga-interstitial defects in GaNyP1−y and AlxGa1−xNyP1−y
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : APS. - 1098-0121 .- 1550-235X. ; 70:12, s. 121201-
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Tidskriftsartikel (refereegranskat)abstract
- Two Ga -interstitial (Gai) defects are identified by optically detected magnetic resonance as common grown-in defects in molecular beam epitaxial GaNyP1−y and AlxGa1−xNyP1−y. Characteristic hyperfine structure arising from spin interaction between an unpaired electron and a Ga nucleus is clearly resolved. The observed strong and nearly isotropic hyperfine interaction reveals an electron wave function of A1 symmetry that is highly localized at the Gai and thus a deep-level defect. Our analysis based on first-principles calculations suggests that these defects are complexes containing one Gai2+ .
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| 19. |
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| 20. |
- Thinh, N.Q., et al.
(författare)
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Properties of Ga-interstitial defects in AlxGa 1-xNyP1-y
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:12
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Tidskriftsartikel (refereegranskat)abstract
- A detailed account of the experimental results from optically detected magnetic resonance (ODMR) studies of grown-in defects in (Al)GaNP alloys, prepared by molecular beam epitaxy, is presented. The experimental procedure and an in-depth analysis by a spin Hamiltonian lead to the identification of two Gai defects (Gai-A and Gai-B). New information on the electronic properties of these defects and the recombination processes leading to the observation of the ODMR signals will be provided. These defects are deep-level defects. In conditions when the defect is directly involved in radiative recombination of the near-infrared photoluminescence band, the energy level of the Gai-B defect was estimated to be deeper than ~1.2 eV from either the conduction or valence band edge. In most cases, however, these defects act as nonradiative recombination centers, reducing the efficiency of light emission from the alloys. They can thus undermine the performance of potential photonic devices. High thermal stability is observed for these defects. ©2005 The American Physical Society.
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| 21. |
- Aharonian, Felix, et al.
(författare)
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Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- Thanks to its high spectral resolution (similar to 5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV He alpha line (w)-the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of similar to 1.3 in the inner similar to 30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, He beta, Ly alpha) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.
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| 22. |
- Aharonian, Felix, et al.
(författare)
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Temperature structure in the Perseus cluster core observed with Hitomi
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- The present paper explains the temperature structure of X-ray emitting plasma in the core of the Perseus cluster based on 1.8-20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) on board the Hitomi Observatory. A series of four observations was carried out, with a total effective exposure time of 338 ks that covered a central region of similar to 7' in diameter. SXS was operated with an energy resolution of similar to 5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions, but also transitions from higher principal quantum numbers were clearly resolved from Si through Fe. That enabled us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single-temperature thermal plasma model in collisional ionization equilibrium, but detailed line-ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with the atomic mass, as well as small differences between the ionization and excitation temperatures for Fe, the only element for which both temperatures could be measured. The best-fit two-temperature models suggest a combination of 3 and 5 keV gas, which is consistent with the idea that the observed small deviations from a single-temperature approximation are due to the effects of projecting the known radial temperature gradient in the cluster core along the line of sight. A comparison with the Chandra/ACIS and the XMM-Newton/RGS results, on the other hand, suggests that additional lower-temperature components are present in the intracluster medium (ICM), but not detectable with Hitomi/SXS giving its 1.8-20 keV energy band.
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| 23. |
- Almeida, Nazare da Silva, et al.
(författare)
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Incubation experiments to constrain the production of methane and carbon dioxide in organic-rich shales of the Permian Irati Formation, Parana Basin
- 2020
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Ingår i: Marine and Petroleum Geology. - : Elsevier. - 0264-8172 .- 1873-4073. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- The Permian Irati Formation in Brazil hosts organic-rich shales and heavy hydrocarbons suitable for biogenic production of methane (CH4) and carbon dioxide (CO2). In this study, shale samples from the irati Formation were used in laboratory incubation experiments performed under different temperatures (22 degrees C, 50 degrees C, 70 degrees C and 80 degrees C) to evaluate the generation of CH4 and CO2 under thermal conditions compatible with biodegradation in shallow gas systems (< 80 degrees C). Despite our laboratory experiments do not represent natural subsurface temperature conditions, it is observed that the concentrations of CH4 and CO2 increase when shale samples are incubated under temperature higher than 22 degrees C. Samples incubated at 80 degrees C presented a maximum CH4 yield of 2.45 ml/t.d (milliliter per ton of shale per day) compared to 0,49 ml/t.d at 22 degrees C, 1.75 ml/t.d at 50 degrees C and 2.09 ml/t.d at 70 degrees C. The same trend of increasing production rates with higher temperatures was observed for CO2, with maximum potential production observed under a laboratory temperature of 80 degrees C, reaching 23.47 ml/t.d. Stable carbon isotopes (delta C-13) on CH4 and CO2 suggest a mixture of thermogenic and secondary microbial gas. However, the measured CH4 and CO2 can be generated through methanogenic degradation of heavy hydrocarbons present in the studied shales, difficulting the use of carbon isotope composition to discriminate between biogenic and thermogenic gases. The studied shale samples showed significant differences in CH4 and CO2 production rates, which are possibly related to the major elements composition of the mineral matrix. Higher CH4 and CO2 production rates occurred in samples with higher amount of sulfur. Besides sulfur, we highlight that others soluble elements in the mineral matrix, such as Ca and Mg, can play an important role for the generation of biogenic CH4 and CO2. The present work intends to alert for the importance of thermal conditions as well as the geochemical composition of the mineral matrix to build conceptual models about shallow gas systems, acting on organic-rich shales in sedimentary basins.
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| 25. |
- Dagnelund, Daniel, 1980-, et al.
(författare)
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Effect of growth conditions on grown-in defect formation and luminescence efficiency in GaInNP epilayers grown by molecular-beam epitaxy.
- 2008
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Ingår i: Physica status solidi (c)Special Issue: E-MRS 2007 Spring Meeting – Symposium F and Conference on Photonic Materials. - Weinheim : Wiley-VCH Verlagsgesellschaft. ; , s. 460-463
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Konferensbidrag (refereegranskat)abstract
- A detailed study of the impact of different growth conditions (i.e. ion bombardment, nitrogen flow and In content) on the defect formation in Ga(In)NP epilayers grown on GaP substrates by solid-source molecular beam epitaxy is performed. Reduced nitrogen ion bombardment during the growth is shown to significantly reduce formation of defects acting as competing recombination centers, such as a Ga interstitial defect and other unidentified defects revealed by optically detected magnetic resonance. Further, high nitrogen flow is found to be even more effective than the ion bombardment in introducing the defects. The incorporation of In by 5.1% is, on the other hand, found not to affect the introduction of defects. The results provide a useful insight into the formation mechanism of the defects that will hopefully shed light on a control of the defect introduction in the alloys by optimizing growth conditions.
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| 26. |
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| 27. |
- Dagnelund, Daniel, 1980-, et al.
(författare)
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Effect of nitrogen ion bombardment on defect formation and luminescence efficiency of GaNP epilayers grown by molecular-beam epitaxy
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:10, s. 101904-
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Tidskriftsartikel (refereegranskat)abstract
- Radiative efficiency of GaNP epilayers grown on GaP substrates by solid-source molecular beam epitaxy is significantly improved by reduced nitrogen ion bombardment during the growth. Based on the results of temperature-dependent photoluminescence (PL) and optically detected magnetic resonance studies (ODMR), the observed improvements are attributed to reduced formation of defects, such as a Ga interstitial related defect and an unidentified defect revealed by ODMR. We demonstrate that these defects act as competing recombination centers, which promote thermal quenching of the PL intensity and result in a substantial (34×) decrease in room-temperature PL intensity. © 2006 American Institute of Physics.
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| 28. |
- Dagnelund, Daniel, 1980-, et al.
(författare)
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Evidence for a phosphorus-related interfacial defect complex at a GaP/GaNP heterojunction
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : The American Physical Society. - 1098-0121 .- 1550-235X. ; 81, s. 115334-
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Tidskriftsartikel (refereegranskat)abstract
- Optically detected magnetic resonance (ODMR) studies of molecular beam epitaxial GaNP/GaP structures reveal presence of a P-related complex defect, evident from its resolved hyperfine interaction between an unpaired electronic spin (S=1/2) and a nuclear spin (I = ½) of a 31P atom. The principal axis of the defect is concluded to be along a <111> crystallographic direction from angular dependence of the ODMR spectrum, restricting the P atom (either a PGa antisite or a Pi interstitial) and its partner in the complex defect to be oriented along this direction. The principal values of the electronic g-tensor and hyperfine interaction tensor are determined as: g┴=2.013, g║=2.002, and A┴=130´10-4 cm-1, A║=330´10-4 cm-1, respectively. The interface nature of the defect is clearly manifested by the absence of the ODMR lines originating from two out of four equivalent <111> orientations. Defect formation is shown to be facilitated by nitrogen ion bombardment under non-equilibrium growth conditions and the defect is thermally stable upon post-growth thermal annealing.
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| 29. |
- Dagnelund, Daniel, 1980-, et al.
(författare)
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Formation of grown-in defects in molecular beam epitaxial Ga(In)NP : effects of growth conditions and post-growth treatments
- 2008
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103, s. 063519-
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Tidskriftsartikel (refereegranskat)abstract
- Effects of growth conditions and post-growth treatments, such as presence of N ions, N2 flow, growth temperature, In alloying, and postgrowth rapid thermal annealing (RTA), on formation of grown-in defects in Ga(In)NP prepared by molecular beam epitaxy are studied in detail by the optically detected magnetic resonance (ODMR) technique. Several common residual defects, such as two Ga-interstitial defects (i.e., Gai-A and Gai-B) and two unidentified defects with a g factor around 2 (denoted by S1 and S2), are closely monitored. Bombardment of impinging N ions on grown sample surface is found to facilitate formation of these defects. Higher N2 flow is shown to have an even more profound effect than a higher number of ions in introducing these defects. Incorporation of a small amount of In (e.g., 5.1%) in GaNP seems to play a minor role in the formation of the defects. In GaInNP with 45% of In; however, the defects were found to be abundant. Effect of RTA on the defects is found to depend on initial configurations of Gai-related defects formed during the growth. In the alloys where the Gai-A and Gai-B defects are absent in the as-grown samples (i.e., GaNP grown at a low temperature of 460 °C), the concentrations of the two Gai defects are found to increase after postgrowth RTA. This indicates that the defects originally introduced in the as-grown alloys have been transformed into the more thermally stable Gai-A and Gai-B during RTA. On the other hand, when the Gai-A and Gai-B are readily abundant (e.g., at higher growth temperatures (>=500 °C), RTA leads to a slight reduction of the Gai-A and Gai-B ODMR signals. The S2 defect is also shown to be thermally stable upon the RTA treatment.
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| 30. |
- Dagnelund, Daniel, et al.
(författare)
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Phosphorus-related interfacial defect complex at a GaP/GaNP heterojunction
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For full exploration of dilute nitrides in device applications, a better understanding and control of defects located at interfaces involving e.g. Ga(In)NP are required. In this work we report on the first identification of a point defect situated at an interface between two semiconductors: GaNP and GaP. The defect is concluded to be a complex involving a P antisite or a P interstitial in its core, partnered with a neighboring impurity/defect aligned along a <111> direction, from detailed angular dependence studies of the optically detected magnetic resonance (ODMR) spectra at both X- and Q-band microwave frequencies. The principal g and A values, g┴=2.013, g║=2.002, A┴=130x10-4 cm-1 and A║=330x10-4 cm-1, are obtained from a spin Hamiltonian analysis. The interface nature of the defect is clearly evident from the absence of the ODMR lines originating from two out of four equivalent <111> orientations. Defect formation is shown to be facilitated by severe nitrogen ion bombardment under non-equilibrium growth conditions during solid-source molecular beam epitaxy and the defect is thermally stable upon post-growth thermal annealing.
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| 31. |
- Dagnelund, Daniel, 1980-, et al.
(författare)
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Spin resonance spectroscopy of grown-in defects in Ga(In)NP alloys
- 2008
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Ingår i: 7th International Conference on Physics of Light-Matter Coupling in Nanostructures, 2007. - : Elsevier Ltd.. ; , s. 620-625
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Konferensbidrag (refereegranskat)abstract
- We employ the optically detected magnetic resonance (ODMR) technique to study and identify important grown-in defects in Ga(In)NP grown by molecular-beam epitaxy (MBE). Several types of defects were revealed from ODMR studies. The dominant defects were found to be related to Ga interstitials, evident form their characteristic hyperfine interaction arising from the spin interaction between the electron and the Ga nucleus. Some other as yet unidentified intrinsic defects were also found to be commonly present in the alloys. The effects of growth conditions (ion bombardment, N2 gas flow, etc.) and post-growth rapid thermal annealing on the formation of these defects were studied in detail, shedding light on the formation mechanism of defects.
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| 32. |
- Ellinor, Patrick T., et al.
(författare)
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Meta-analysis identifies six new susceptibility loci for atrial fibrillation
- 2012
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 44:6, s. 88-670
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Tidskriftsartikel (refereegranskat)abstract
- Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death(1). We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 10,030 subjects without atrial fibrillation (P < 5 x 10(-8)). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.
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| 33. |
- Eriksson, Tobias A., et al.
(författare)
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Digital self-coherent continuous variable quantum key distribution system
- 2020
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Ingår i: Optics InfoBase Conference Papers. - : Optica Publishing Group.
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Konferensbidrag (refereegranskat)abstract
- We investigate a continuous variable quantum key distribution system with digital tracking of both polarization and phase. Stable operation over 25km for 36 hours with secret key rates between 1.9 and 2.8 Mbit/s is demonstrated.
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| 34. |
- Izadifard, Morteza, 1965-, et al.
(författare)
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Effects of rapid thermal annealing on optical properties of GaNxP1−x alloys grown by solid source molecular beam epitaxy
- 2005
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Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 20:5, s. 353-356
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Tidskriftsartikel (refereegranskat)abstract
- Temperature-dependent photoluminescence (PL), PL excitation and time-resolved PL measurements were employed to study the effects of rapid thermal annealing (RTA) on optical properties of GaNxP1−x alloys grown by solid source molecular beam epitaxy. A substantial increase in radiative efficiency of GaNP epilayers, which is especially pronounced for the high-energy PL component, was achieved after RTA and is attributed to annealing out of competing non-radiative centres. The latter is evident from reduced quenching of the PL intensity with increasing measurement temperature, which results in a strong increase (up to 18 times) in the PL intensity at room temperature (RT), as well as from a substantial increase in carrier lifetime at RT deduced from time-resolved PL measurements.
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| 35. |
- Izadifard, Morteza, 1965-, et al.
(författare)
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Effects of rapid thermal annealing on optical quality of GaNP alloys
- 2004
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Ingår i: EMRS-2004 Spring Meeting,2004. - : Institution of Engineering and Technology (IET). ; , s. 335-
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Konferensbidrag (refereegranskat)abstract
- Significant improvements in radiative efficiency of GaNP epilayers grown on GaP substrates by solid-source molecular beam epitaxy (MBE) are achieved by post-growth rapid thermal annealing (RTA). From temperature-dependent CW and time-resolved photoluminescence (PL) spectroscopies combined with PL excitation measurements, the observed improvements are attributed to annealing out of competing nonradiative centres. This conclusion is supported by the following experimental evidence: reduced thermal quenching of the PL intensity resulting in a substantial (up to 18 times) increase at room temperature (RT) after RTA, and simultaneous improvements in carrier lifetime at RT deduced from time-resolved PL measurements.
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| 36. |
- Izadifard, Morteza, 1965-, et al.
(författare)
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Evaluation of optical quality and defect properties of GaNxP1−x alloys lattice matched to Si
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85, s. 6347-
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Tidskriftsartikel (refereegranskat)abstract
- By using a variety of optical characterization techniques, including cathodoluminescence, temperature-dependent cw- and time-resolved photoluminescence (PL), and PL excitation spectroscopies, high optical quality of the GaN0.018P0.982 epilayers lattice matched to Si substrates is demonstrated and is shown to be comparable to that of the “state-of-the-art” GaNP alloys grown on GaP substrates. The growth of GaNP on Si is, however, found to facilitate the formation of several point defects, including complexes involving Ga interstitial atoms (Gai).
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| 37. |
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| 38. |
- Kaur, H., et al.
(författare)
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Differential Role of HAMP-like Linkers in Regulating the Functionality of the Group III Histidine Kinase DhNik1p
- 2014
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 289:29, s. 20245-20258
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Tidskriftsartikel (refereegranskat)abstract
- Nik1 orthologs are sensor kinases that function upstream of the high osmolarity glycerol/p38 MAPK pathway in fungi. They contain a poly-HAMP module at their N terminus, which plays a pivotal role in osmosensing as well as fungal death upon exposure to fludioxonil. DhNik1p is a typical member of this class that contains five HAMP domains and four HAMP-like linkers. We investigated the contribution of each of the HAMP-like linker regions to the functionality of DhNik1p and found that the HAMP4b linker was essential as its deletion resulted in the complete loss of activity. Replacement of this linker with flexible peptide sequences did not restore DhNik1p activity. Thus, the HAMP-like sequence and possibly structural features of this linker region are indispensable for the kinase activity of DhNik1p. To gain insight into the global shape of the poly-HAMP module in DhNik1p (HAMP1-5), multi-angle laser light and small angle x-ray scattering studies were carried out. Those data demonstrate that the maltose-binding protein-tagged HAMP1-5 protein exist as a dimer in solution with an elongated shape of maximum linear dimension similar to 365 angstrom. Placement of a sequence similarity based model of the HAMP1-5 protein inside experimental data-based models showed how two chains of HAMP1-5 are entwined on each other and the overall structure retained a periodicity. Normal mode analysis of the structural model is consistent with the H4b linker being a key to native-like collective motion in the protein. Overall, our shape-function studies reveal how different elements in the HAMP1-5 structure mediate its function.
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| 39. |
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| 40. |
- Padamsee, Mahajabeen, et al.
(författare)
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The genome of the xerotolerant mold Wallemia sebi reveals adaptations to osmotic stress and suggests cryptic sexual reproduction
- 2012
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Ingår i: Fungal Genetics and Biology. - : Elsevier BV. - 1087-1845 .- 1096-0937. ; 49:3, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- Wallemia (Wallemiales, Wallemiomycetes) is a genus of xerophilic Fungi of uncertain phylogenetic position within Basidiomycota. Most commonly found as food contaminants, species of Wallemia have also been isolated from hypersaline environments. The ability to tolerate environments with reduced water activity is rare in Basidiomycota. We sequenced the genome of W. sebi in order to understand its adaptations for surviving in osmotically challenging environments, and we performed phylogenomic and ultrastructural analyses to address its systematic placement and reproductive biology. W. sebi has a compact genome (9.8Mb), with few repeats and the largest fraction of genes with functional domains compared with other Basidiomycota. We applied several approaches to searching for osmotic stress-related proteins. In silico analyses identified 93 putative osmotic stress proteins; homology searches showed the HOG (High Osmolarity Glycerol) pathway to be mostly conserved. Despite the seemingly reduced genome, several gene family expansions and a high number of transporters (549) were found that also provide clues to the ability of W. sebi to colonize harsh environments. Phylogenetic analyses of a 71-protein dataset support the position of Wallemia as the earliest diverging lineage of Agaricomycotina, which is confirmed by septal pore ultrastructure that shows the septal pore apparatus as a variant of the Tremella-type. Mating type gene homologs were identified although we found no evidence of meiosis during conidiogenesis, suggesting there may be aspects of the life cycle of W. sebi that remain cryptic.
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| 41. |
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| 42. |
- Rademacher, G., et al.
(författare)
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10.66 Peta-Bit/s Transmission over a 38-Core-Three-Mode Fiber
- 2020
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Ingår i: 2020 Optical Fiber Communications Conference and Exhibition, OFC 2020 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- We demonstrate transmission of 368-WDM-38-core-3-mode × 24.5-GBaud 64- and 256-QAM signals over 13 km. Record data-rate and spectral-efficiency of 1158.7 b/s/Hz were enabled by a low DMD 38-core-3-mode fiber with high uniformity amongst cores.
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| 43. |
- Rademacher, G., et al.
(författare)
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High capacity transmission with few-mode fibers
- 2019
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 37:2, s. 425-432
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally investigate high-capacity few-mode fiber transmission for short and medium-haul optical links. In separate experiments, we demonstrate C + L band transmission of 283 Tbit/s over a single 30 km span and recirculating loop transmission of 159 Tbit/s over 1045 km graded-index three mode fiber. The first experiment reached a data-rate per fiber mode within 90% of the record data-rates reported in the same transmission bands for single-mode fibers. The second experiment demonstrated the feasibility of reaching high data-rates over long distance few-mode fiber transmission, despite strong impairments due to mode-dependent loss and differential mode delay.
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| 44. |
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| 45. |
- Shimada, A., et al.
(författare)
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Neural signal transmission measurements with a conductive polymer microelectrode array
- 2009
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Ingår i: IEEJ Transactions on Electronics, Information and Systems. - : Institute of Electrical Engineers of Japan (IEE Japan). - 0385-4221 .- 1348-8155. ; 129:2, s. 267-271+10
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Tidskriftsartikel (refereegranskat)abstract
- The neural activity of dissociated cultures of mouse cerebral cortical neurons was measured with a conductive polymer microelectrode array. Each electrode was electrochemically polymerized from (3,4-ethylenedioxythiophene)- poly(styrenesulfonate) and ethylenedioxythiophene on indium tin oxide electrodes. The spike activity of the cortical neurons was measured with the conducting polymer MEA and spike train cross-correlograms were calculated to predict the type of synaptic connection. Both excitatory and inhibitory synaptic connections were identified after 6-8 days in vitro. These results show that it is possible to determine the interaction between excitatory and inhibitory neurons in relation to information processing with this new polymer electrode.
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| 46. |
- Vorona, Igor, 1967-, et al.
(författare)
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Intrinsic paramagnetic defects in GaNP alloys grown on silicon
- 2006
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Ingår i: 210th ECS Meeting Volume 3, Issue 5. - : Electrochemical Society. ; , s. 231-236
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Wepresent our recent results of grown-in defects in the GaNPalloy lattice matched to Si, by optically detected magnetic resonance.One of the defects was identified as the Gai-B complex,commonly formed in dilute nitrides. The remaining defects are suggestedto be probably related to intrinsic defects as well.
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