| 1. |
- Boström, Magnus, 1972-, et al.
(författare)
-
Conditions for Transformative Learning for Sustainable Development : A Theoretical Review and Approach
- 2018
-
Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 10:12
-
Tidskriftsartikel (refereegranskat)abstract
- Continued unsustainability and surpassed planetary boundaries require not only scientific and technological advances, but deep and enduring social and cultural changes. The purpose of this article is to contribute a theoretical approach to understand conditions and constraints for societal change towards sustainable development. In order to break with unsustainable norms, habits, practices, and structures, there is a need for learning for transformation, not only adaption. Based on a critical literature review within the field of learning for sustainable development, our approach is a development of the concept of transformative learning, by integrating three additional dimensions—Institutional Structures, Social Practices, and Conflict Perspectives. This approach acknowledges conflicts on macro, meso, and micro levels, as well as structural and cultural constraints. It contends that transformative learning is processual, interactional, long-term, and cumbersome. It takes place within existing institutions and social practices, while also transcending them. The article adopts an interdisciplinary social science perspective that acknowledges the importance of transformative learning in order for communities, organizations, and individuals to be able to deal with global sustainability problems, acknowledging the societal and personal conflicts involved in such transformation.
|
|
| 2. |
- Berg, Erik, et al.
(författare)
-
A Statistical Multiprocessor Cache Model
- 2006
-
Ingår i: Proc. International Symposium on Performance Analysis of Systems and Software. - Piscataway, NJ : IEEE. - 1424401860 ; , s. 89-99, s. 89-99
-
Konferensbidrag (refereegranskat)
|
|
| 3. |
- Berg, Erik, et al.
(författare)
-
A Statistical Multiprocessor Cache Model
- 2005
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The introduction of general purpose microprocessors running multiple threads will put a focus on methods and tools helping a programmer to write efficient parallel applications. Such tool should be fast enough to meet a software developer's need for short turn-around time, but also accurate and flexible enough to provide trend-correct and intuitive feedback. This paper describes an efficient and flexible approach for modeling the memory system of a multiprocessor, such as those of chip multiprocessors (CMPs). Sparse data is sampled during a multithreaded execution. The data collected consist of the reuse distance and invalidation distribution for a small subset of the memory accesses. Based on the sampled data from a single run, a new mathematical formula can be used to estimate the miss rate for a memory hierarchy built from caches of arbitrarily size, cacheline size and degree of sharing. The formula further divides the misses into six categories to further aid the software developer. The method is evaluated using a large number of commercial and technical multithreaded applications. The result produced by our algorithm fed with sparse sampling data is shown to be consistent with results gathered during traditional architecture simulation.
|
|
| 4. |
- Berg, Erik, 1970-
(författare)
-
Efficient and Flexible Characterization of Data Locality through Native Execution Sampling
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Data locality is central to modern computer designs. The widening gap between processor speed and memory latency has introduced the need for a deep hierarchy of caches. Thus, the performance of an application is to a large extent dependent on the amount of data locality the caches can exploit. Some data locality comes naturally from the way most programs are written and the way their data is allocated in the memory. Compilers further try to create data locality by loop transformations and optimized data layout. Different ways of writing a program and/or laying out its data may improve an application’s locality even more. However, it is far from obvious how such a locality optimization can be achieved, especially since the optimizing compiler may have left the optimization job half done. Thus, efficient tools are needed to guide the software developers on their quest for data locality. The main contribution of this dissertation is a sample-based novel method for analyzing the data locality of an application. Very sparse data is collected during a single execution of the studied application. The sparse sampling adds a minimum overhead to the execution time, which enables complex applications running realistic data sets to be studied. The architecturalindependent information collected during the execution is fed to a mathematical cache model for predicting the cache miss ratio. The sparsely-collected data can be used to characterize the application’s data locality in respect to almost any possible cache hierarchy, such as complicated multiprocessor memory systems with multilevel cache hierarchies. Any combination of cache size, cache line size and degree of sharing can be modeled. Each new modeled design point takes only a fraction of a second to evaluate, even though the application from which the sampled data was collected may have executed for hours. This makes the tool not just usable for software developers, but also for hardware developers who need to evaluate a huge memory-system design space. We also discuss different ways of presenting data-locality information to a programmer in an intuitive and easily interpreted way. Some of the locality metrics we introduce utilize the flexibility of our algorithm and its ability to vary different cache parameters for one run. The dissertation also presents several prototype implementations of tools for profiling the memory system.
|
|
| 5. |
- Berg, Erik, et al.
(författare)
-
Efficient Data-Locality Analysis of Long-Running Applications
- 2004
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Analysis of application data cache behavior is important for program optimization and architectural design decisions. Current methods include hardware monitoring and simulation, but these methods lack from either limited flexibility or large run-time overhead that prevents realistic workloads. This paper describes a new fast and flexible tool based on StatCache. This tool is based on a probabilistic cache model instead of a functional cache simulator and use sparsely sampled run-time information instead of complete traces or sampled contiguous subtraces. A post-run analyzer calculates miss ratios of fully associative caches of arbitrary size and cache line size, from statistics gathered at a single run. It can also produce various data-locality metrics and give data-structure centric data-locality figures. The implementation utilizes simple-hardware and operating-system support available in most operating systems and runs uninstrumented optimized code. We evaluate the method using the SPEC benchmark suite using the largest (ref) input sets and show that the accuracy is high. We also show the run-time overhead for this flexible “cache simulator” to be less than 20% for long-running applications, much faster than current simulators.
|
|
| 6. |
- Berg, Erik, et al.
(författare)
-
Fast Data-Locality Profiling of Native Execution
- 2005
-
Ingår i: ACM SIGMETRICS Performance Evaluation Review. - : Association for Computing Machinery (ACM). - 0163-5999. ; 33:1, s. 169-180
-
Tidskriftsartikel (refereegranskat)abstract
- Performance tools based on hardware counters can efficiently profile the cache behavior of an application and help software developers improve its cache utilization. Simulator-based tools can potentially provide more insights and flexibility and model many different cache configurations, but have the drawback of large run-time overhead.We present StatCache, a performance tool based on a statistical cache model. It has a small run-time overhead while providing much of the flexibility of simulator-based tools. A monitor process running in the background collects sparse memory access statistics about the analyzed application running natively on a host computer. Generic locality information is derived and presented in a code-centric and/or data-centric view.We evaluate the accuracy and performance of the tool using ten SPEC CPU2000 benchmarks. We also exemplify how the flexibility of the tool can be used to better understand the characteristics of cache-related performance problems.
|
|
| 7. |
- Berg, Erik, et al.
(författare)
-
Low-Overhead Spatial and Temporal Data Locality Analysis
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Performance is getting increasingly sensitive to cache behavior because of the growing gap between processor cycle time and memory latency. To improve performance, applications need to be optimized for data locality. Run-time analysis of spatial and temporal data locality can be used to facilitate this and should help both manual tuning and feedback-based compiler optimizations. Identifying cache behavior of individual data structures further enhances the optimization process. Current methods to perform such analysis include simulation combined with set sampling or time sampling, and hardware monitoring. Sampling often suffers from either poor accuracy or large run-time overhead, while hardware measurements have limited flexibility.We present DLTune, a prototype tool that performs spatial and temporal data-locality analysis in run time. It measures both spatial and temporal locality for the entire application and individual data structures in a single run, and effectively exposes poor data locality based on miss ratio estimates of fully-associative caches. The tool is based on an elaborate and novel sampling technique that allows all information to be collected in a single run with an overall sampling rate as low as one memory reference in ten million and an average slowdown below five on large workloads.
|
|
| 8. |
- Berg, Erik
(författare)
-
Methods for run time analysis of data locality
- 2003
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The growing gap between processor clock speed and DRAM access time puts new demands on software and development tools. Deep memory hierarchies and high cache miss penalties in present and emerging computer systems make execution time sensitive to data locality. Therefore, developers of performance-critical applications and optimizing compilers must be aware of data locality and maximize cache utilization to produce fast code. To aid the optimization process and help understanding data locality, we need methods to analyze programs and pinpoint poor cache utilization and possible optimization opportunities.Current methods for run-time analysis of data locality and cache behavior include functional cache simulation, often combined with set sampling or time sampling, other regularity metrics based on strides and data streams, and hardware monitoring. However, they all share the trade-off between run-time overhead, accuracy and explanatory power.This thesis presents methods to efficiently analyze data locality at run time based on cache modeling. It suggests source-interdependence profiling as a technique for examining the cache behavior of applications and locating source code statements and/or data structures that cause poor cache utilization. The thesis also introduces a novel statistical cache-modeling technique, StatCache. Rather than implementing a functional cache simulator, StatCache estimates the miss ratios of fully-associative caches using probability theory. A major advantage of the method is that the miss ratio estimates can be based on very sparse sampling. Further, a single run of an application is enough to estimate the miss ratio of caches of arbitrary sizes and line sizes and to study both spatial and temporal data locality.
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Berg, Erik, et al.
(författare)
-
StatCache: A Probabilistic Approach to Efficient and Accurate Data Locality Analysis
- 2004
-
Ingår i: 2004 IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS-2004).
-
Konferensbidrag (refereegranskat)abstract
- The widening memory gap reduces performance of applications with poor data locality. Therefore, there is a need for methods to analyze data locality and help application optimization. In this paper we present Stat-Cache, a novel sampling-based method for performing data-locality analysis on realistic workloads. StatCache is based on a probabilistic model of the cache, rather than a functional cache simulator. It uses statistics from a single run to accurately estimate miss ratios of fully-associative caches of arbitrary sizes and generate working-set graphs. We evaluate StatCache using the SPEC CPU2000 benchmarks and show that StatCache gives accurate results with a sampling rate as low as 10^(-4). We also provide a proof-of-concept implementation, and discuss potentially very fast implementation alternatives.Available as PDF (126 kB)
|
|
| 12. |
- Berg, Erik, et al.
(författare)
-
StatCache: A Probabilistic Approach to Efficient and Accurate Data Locality Analysis
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The widening memory gap reduces performance of applications with poor data locality. This problem can be analyzed using working-set graphs. Current methods to generate such graphs include set sampling and time sampling, but cold start effects and unrepresentative set selection impair accuracy.In this paper we present StatCache, a novel sample-based method that can perform data-locality analysis on realistic workloads. During the execution of an application, sparse discrete memory accesses are sampled, and their reuse distances are measured using a simple watchpoint mechanism. StatCache uses the information collected from a single run to accurately estimate miss ratios of fully-associative caches of arbitrary sizes and generates working-set graphs.We evaluate StatCache using the SPEC CPU2000 benchmarks and show that StatCache gives accurate results with a sampling rate as low as 10-4. We also provide a proof-of-concept implementation, and discuss potentially very fast implementation alternatives.
|
|
| 13. |
- Berg, Håkan, et al.
(författare)
-
Characterization of antibodies for quantitative determination of spiggin protein levels in male and female three-spined stickleback (Gasterosteus aculeatus)
- 2009
-
Ingår i: Reproductive Biology and Endocrinology. - : BioMed Central (BMC). - 1477-7827. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- Spiggin is an adhesive glycoprotein produced in the kidney of sticklebacks during the breeding season and is subsequently secreted into the urinary bladder from where it is employed for nest building. Since the production of the protein has been shown to be under androgenic control, spiggin has been suggested to be a useful biomarker for androgenic substances in the environment. In this study, two polyclonal spiggin antibodies based on synthetic peptides and one polyclonal antibody directed against native spiggin have been characterized. The antibodies ability to identify spiggin was investigated by quantitative immunoassay. For both peptide antibodies the quantification range was determined to be between 1 and 80 ng spiggin and determination of renal spiggin levels from immature and mature males displayed a 15-fold increase in total spiggin content of the kidney resulting in a 6-fold increase in male kidney weight due to hypertrophy. The kidney somatic index (KSI) was found to correlate well with the total renal spiggin content and therefore it appears that KSI in sticklebacks could be used as an initial method to identify substances displaying androgenic effects. Furthermore, western blot analysis revealed that the polyclonal antibodies recognize different spiggin isoforms and that spiggin can be detected in the urinary bladder and kidney of both males and female sticklebacks. In order to develop a quantitative detection method for native spiggin it is necessary to produce a standard that can be used in a bioassay. Due to the adhesive and polymerization characteristics of spiggin the protein is difficult to use as a standard in bioassays. So far spiggin has been shown to exist in at least 14 isoforms, all of which contain polymerization domains. To overcome the solubility problem we have produced recombinant spiggin gamma, with only one polymerization domain, that can be expressed in E. coli. Western blot analysis demonstrated that the polyclonal antibodies were able to detect recombinant spiggin gamma protein in bacterial cell lysate, suggesting that it may be developed into a useful source of standard spiggin to be used for quantitative determination of androgen induced spiggin production in sticklebacks.
|
|
| 14. |
- Berg, Jan-Erik, 1957-, et al.
(författare)
-
Refining gentleness - a key to bulky CTMP
- 2022
-
Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 37:2, s. 349-355
-
Tidskriftsartikel (refereegranskat)abstract
- Chemithermomechanical pulp (CTMP) is often used in middle layers of multiply paperboards due to its high bulk at specified strength. Such a CTMP should consist of well-separated undamaged fibres with sufficient bonding capacity. The basic objective of this work is to examine the effect of refining on bulk, taking into account conditions such as temperature, sulphonation, refining gap and refiner size. First stage CTMP made from Norway spruce (Picea abies) were produced in pilot and mill scale trials. Two new parameters, Equivalent temperature related to softness and Refining gentleness are introduced that take into account refining conditions as actual temperature, softening temperature, bound sulphonate content, refining gap and refiner diameter. The results show that bulk increases linearly with refining gentleness.
|
|
| 15. |
- Berg, Martin, et al.
(författare)
-
A transmission line method for evaluation of vertical InAs nanowire contacts
- 2015
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 107:23
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a method for metal contact characterization to vertical semiconductor nanowires using the transmission line method (TLM) on a cylindrical geometry. InAs nanowire resistors are fabricated on Si substrates using a hydrogen silsesquioxane (HSQ) spacer between the bottom and top contact. The thickness of the HSQ is defined by the dose of an electron beam lithography step, and by varying the separation thickness for a group of resistors, a TLM series is fabricated. Using this method, the resistivity and specific contact resistance are determined for InAs nanowires with different doping and annealing conditions. The contacts are shown to improve with annealing at temperatures up to 300 degrees C for 1min, with specific contact resistance values reaching down to below 1 Omega mu m(2). (C) 2015 AIP Publishing LLC.
|
|
| 16. |
- Berg, Martin, et al.
(författare)
-
Electrical Characterization and Modeling of Gate-Last Vertical InAs Nanowire MOSFETs on Si
- 2016
-
Ingår i: IEEE Electron Device Letters. - 0741-3106. ; 37:8, s. 966-969
-
Tidskriftsartikel (refereegranskat)abstract
- Vertical InAs nanowire transistors are fabricated on Si using a gate-last method, allowing for lithography-based control of the vertical gate length. The best devices combine good ON- and OFF-performance, exhibiting an ON-current of 0.14 mA/μm, and a sub-threshold swing of 90 mV/dec at 190 nm LG. The device with the highest transconductance shows a peak value of 1.6 mS/μm. From RF measurements, the border trap densities are calculated and compared between devices fabricated using the gate-last and gate-first approaches, demonstrating no significant difference in trap densities. The results thus confirm the usefulness of implementing digital etching in thinning down the channel dimensions.
|
|
| 17. |
- Berg, Martin, et al.
(författare)
-
InAs nanowire MOSFETs in three-transistor configurations: single balanced RF down-conversion mixers.
- 2014
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:48
-
Tidskriftsartikel (refereegranskat)abstract
- Integration of III-V semiconductors on Si substrates allows for the realization of high-performance, low power III-V electronics on the Si-platform. In this work, we demonstrate the implementation of single balanced down-conversion mixer circuits, fabricated using vertically aligned InAs nanowire devices on Si. A thin, highly doped InAs buffer layer has been introduced to reduce the access resistance and serve as a bottom electrode. Low-frequency voltage conversion gain is measured up to 7 dB for a supply voltage of 1.5V. Operation of these mixers extends into the GHz regime with a [Formula: see text] cut-off frequency of 2 GHz, limited by the optical lithography system used. The circuit dc power consumption is measured at 3.9 mW.
|
|
| 18. |
- Berg, Martin, et al.
(författare)
-
Self-aligned, gate-last process for vertical InAs nanowire MOSFETs on Si
- 2016
-
Ingår i: Technical Digest - International Electron Devices Meeting, IEDM. - 9781467398930 ; 2016-February
-
Konferensbidrag (refereegranskat)abstract
- In this work, we present a novel self-aligned gate-last fabrication process for vertical nanowire metal-oxide-semiconductor field-effect transistors. The fabrication method allows for exposure dose-defined gate lengths and a local diameter reduction of the intrinsic channel segment, while maintaining thicker highly doped access regions. Using this process, InAs nanowire transistors combining good on-and off-performance are fabricated demonstrating Q = gm,max/SS = 8.2, which is higher than any previously reported vertical nanowire MOSFET.
|
|
| 19. |
- Berg, Martin, et al.
(författare)
-
Single Balanced Down-Conversion Mixer Utilizing Indium Arsenide Nanowire MOSFETs
- 2014
-
Ingår i: 26th International Conference on Indium Phosphideand Related Materials (IPRM). - 1092-8669.
-
Konferensbidrag (refereegranskat)abstract
- We have fabricated single balanced down-conversion mixer circuits using InAs nanowire MOSFETs as both active and passive devices. This is achieved by a combination of electron beam lithography and UV-lithography with a line width of 12 mu m. The circuits exhibit a low frequency voltage conversion gain of 6 dB, a -3 dB cutoff frequency of 2 GHz and a power consumption of 3.8 mW, while operating at a supply voltage of 1.5 V. The circuits retain circuit functionality even for a supply voltage of 1 V.
|
|
| 20. |
- Berg, Åke, et al.
(författare)
-
Assessing agri-environmental schemes for semi-natural grasslands during a 5-year period: can we see positive effects for vascular plants and pollinators?
- 2019
-
Ingår i: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 28, s. 3989-4005
-
Tidskriftsartikel (refereegranskat)abstract
- An important function of agri-environmental schemes (AES) is to change management of pastures to better conserve biodiversity. However, the effects of most AES on biodiversity are poorly understood, especially when it comes to effects of AES management over time. The main aim of this study is to investigate if the species richness and abundance of grassland specialists of vascular plants and two important insect pollinator groups (bumblebees and butterflies) differ over time (5 years) in pastures with AES management (two value levels; general values and special values) and pastures without AES management. We also investigate if local vegetation characteristics and landscape composition relate to species richness in semi-natural grasslands. Using data from more than 400 sites we found that species richness of vascular plants (grassland specialists) was higher in pastures with AES management (for special and general values) compared to those without AES, which implies that these schemes do have value of the conservation of plant diversity. However, species richness and abundance of butterflies (grassland specialists) and bumblebees (all species) did not differ significantly among the three AES categories. We found no evidence that the type of AES management caused any changes in species richness of plants, butterflies or bumblebees during the 5 year period of our investigation. It appears that AES management that encourages uniform and minimum levels of grazing can have both positive and negative effects on biodiversity. For example, pollinators may benefit from a lower grazing intensity that could increase flower richness and heterogeneity in vegetation height. However, low grazing intensity may lead to increased cover of trees and shrubs, which can have negative effects for both insect pollinators and vascular plants. The effects of landscape composition were weak and only species richness of bumble bees were associated with landscape composition. Designing management regimes to maintain suitably heterogeneous vegetation layer, and continued long-term monitoring of biodiversity will be critical for safeguarding culturally and functionally important semi-natural grasslands.
|
|
| 21. |
- Brijs, J., et al.
(författare)
-
Humane slaughter of African sharptooth catfish (Clarias gariepinus): Effects of various stunning methods on brain function
- 2021
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 531
-
Tidskriftsartikel (refereegranskat)abstract
- © 2020 The Authors Common slaughter procedures for African sharptooth catfish (Clarias gariepinus) include asphyxiation, ice chilling and exsanguination, which may all cause substantial suffering over prolonged periods of time before death. Therefore, comprehensive evaluations of potentially more humane slaughter procedures for this species are urgently needed. Here, we use a non-invasive electroencephalographic (EEG) method to assess the state of sensibility in African sharptooth catfish in response to various stunning methods (e.g. ice chilling, electrical stunning, electrical stunning followed by exsanguination, percussive stunning, and immersion in isoeugenol). Based on the abolition of visually evoked responses (VERs) on the EEG, ice slurry immersion induced insensibility between 2.6 and 7.6 min, during which catfish exhibited aversive behaviours. Once VERs were lost, they remained absent so long as catfish remained immersed in the ice slurry. Electrical stunning (i.e. exposure to ~1.7 A dm−2 at a water conductivity of ~997 μS cm−1) induced insensibility immediately but not irreversibly. Depending on the duration of the stun (i.e. from 1 to 10 s), catfish either regained VERs immediately or within 4.9 min after the completion of the electrical insult. However, when a 10 s electrical stun was immediately followed by exsanguination and immersion in an ice slurry, the duration of insensibility was sufficient to humanely kill catfish. When administered correctly, manual percussive stunning with a fish priest induced insensibility immediately and irreversibly. However, 36% of catfish regained VERs, which is likely explained by the difficulty associated with administering an accurate manual percussive stun of sufficient force on a live and struggling catfish. Catfish appeared to be sedated following immersion in isoeugenol (i.e. catfish were calm and easy to handle), yet VERs remained present at doses exceeding that recommended for euthanasia in salmonids, which indicates that this substance may not be suitable for stunning catfish. However, the potential for using isoeugenol as a pre-stunning sedative for improving handleability and reducing handling stress of this species warrants further investigation. In conclusion, this study clearly demonstrates that when singularly administered, none of the abovementioned stunning methods could reliably induce insensibility immediately and/or irreversibly without welfare implications. Yet, our findings indicate that these shortcomings can be resolved by using a combination of methods. This could include an electrical or percussive stun to immediately induce insensibility that should be immediately followed by exsanguination and immersion in an ice slurry to maintain insensibility until death.
|
|
| 22. |
- Brijs, J., et al.
(författare)
-
In vivo aerobic metabolism of the rainbow trout gut and the effects of an acute temperature increase and stress event
- 2018
-
Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 221:14
-
Tidskriftsartikel (refereegranskat)abstract
- The fish gut is responsible for numerous potentially energetically costly processes, yet little is known about its metabolism. Here, we provide the first in vivo measurements of aerobic metabolism of the gut in a teleost fish by measuring gut blood flow, as well as arterial and portal venous oxygen content. At 10 degrees C, gut oxygen uptake rate was 4.3 +/- 0.5 ml O-2 h(-1) kg(-1) (similar to 11 % of whole-animal oxygen uptake). Following acute warming to 15 degrees C, gut blood flow increased similar to 3.4-fold and gut oxygen uptake rate increased similar to 3.7-fold (16.0 +/- 3.3 ml O-2 h(-1) kg(-1)), now representing similar to 25% of whole-animal oxygen uptake. Although gut blood flow decreased following an acute stress event at 15 degrees C, gut oxygen uptake remained unchanged as a result of a similar to 2-fold increase in oxygen extraction. The high metabolic thermal sensitivity of the gut could have important implications for the overall aerobic capacity and performance of fish in a warming world and warrants further investigation.
|
|
| 23. |
- Brijs, J., et al.
(författare)
-
Prevalence and severity of cardiac abnormalities and arteriosclerosis in farmed rainbow trout (Oncorhynchus mykiss)
- 2020
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 526
-
Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular disease may pose a major threat to the health and welfare of farmed fish. By investigating a range of established cardiovascular disease indicators, we aimed to determine the prevalence, severity and consequences of this affliction in farmed rainbow trout (Oncorhynchus mykiss) from an open cage farm in the Baltic Sea, an open cage farm in a freshwater lake, and a land-based recirculating aquaculture system. We also aimed to identify environmental, anthropogenic and physiological factors contributing towards the development of the disease. The majority of trout possessed enlarged hearts with rounded ventricles (mean height:width ratios of 1.0–1.1 c.f. ~1.3 in wild fish) and a high degree of vessel misalignment (mean angles between the longitudinal ventricular axis and the axis of the bulbus arteriosus of 28–31 °c.f. ~23° in wild fish). The prevalence and severity of coronary arteriosclerosis was also high, as 92–100% of fish from the different aquaculture facilities exhibited coronary lesions. Mean lesion incidence and severity indices were 67–95% and 3.1–3.9, respectively, which resulted in mean coronary arterial blockages of 19–32%. To evaluate the functional significance of these findings, we modelled the effects of arterial blockages on coronary blood flow and experimentally tested the effects of coronary occlusion in a sub-sample of fish. The observed coronary blockages were estimated to reduce coronary blood flow by 34–54% while experimental coronary occlusion adversely affected the electrocardiogram of trout. Across a range of environmental (water current, predation), anthropogenic (boat traffic intensity, hatchery of origin, brand of feed pellets) and physiological factors (condition factor, haematological and plasma indices), the hatchery of origin was the main factor contributing towards the observed variation in the development of cardiovascular disease. Therefore, further research on the effects of selective breeding programs and rearing strategies on the development of cardiovascular disease is needed to improve the welfare and health of farmed fish. © 2020 The Authors
|
|
| 24. |
- Brijs, J., et al.
(författare)
-
Prospects and pitfalls of using heart rate bio-loggers to assess the welfare of rainbow trout (Oncorhynchus mykiss) in aquaculture
- 2019
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 509, s. 188-197
-
Tidskriftsartikel (refereegranskat)abstract
- - Investigating real-time stress responses during common aquaculture practices is necessary for improving the welfare of farmed fish. Recently, Star-Oddi DST milli-HRT bio-loggers capable of measuring heart rate (as an indicator for stress) in freely swimming fish have proved to be useful in this regard. However, despite the growing popularity of these devices, they have not yet been stringently evaluated and validated for use in fish. The present study is the first to do so by simultaneously recording heart rate of a commercially important salmonid species (rainbow trout, Oncorhynchus mykiss) using the abovementioned bio-loggers, as well as an established non-invasive wireless heart rate recording technique that has been demonstrated to provide more accurate recordings than those collected using traditional methods requiring a physical connection to recording equipment. The measurement error of the bio-loggers was <1 beat min −1 irrespective of the sampling period when only using measurements graded with the highest quality index (QI 0 ) and it is advised that only QI 0 measurements be used as inclusion of poorer quality measurements (QI 1–3 ) markedly reduce measurement accuracy. Furthermore, sufficiently long recovery periods should be employed prior to collecting data with these devices in salmonids, as anaesthesia and surgical implantation of bio-loggers resulted in transiently elevated resting heart rates for >72 h. Following the successful validation of these bio-loggers, the effects of common aquaculture practices such as netting, grouping and enforced activity on the cardiac performance of freely swimming rainbow trout were investigated. Prior to the subsequent exposure to the abovementioned stressors, mean heart rates of trout were ~42 beats min −1 . Following netting, trout increased heart rates by 57%, which recovered within 3 h. Grouping subsequently induced a more pronounced and prolonged stress response, as heart rates initially increased by 86% and then remained elevated throughout the 8 h recovery period. Consequently, trout were only able to further increase heart rates by 7% following enforced activity. This diminished cardiac response demonstrates a situation where the cumulative allostatic load induced by prior stressors is approaching a level where the animal struggles to perform normal physiological processes in the face of further challenges. These findings are important for the aquaculture industry as exposure to multiple stressors without sufficient recovery times has the potential to result in the collapse of cardiac scope, which combined with unfavourable environmental conditions could lead to increased mortality. © 2019 Elsevier B.V.
|
|
| 25. |
- Brijs, J., et al.
(författare)
-
Remote physiological monitoring provides unique insights on the cardiovascular performance and stress responses of freely swimming rainbow trout in aquaculture
- 2019
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9:1
-
Tidskriftsartikel (refereegranskat)abstract
- Investigating the mechanisms that fish employ to maintain homeostasis in their everyday life requires measurements of physiological and behavioural responses in the field. With multivariate bio-loggers, we continuously measured gastrointestinal blood flow (GBF), heart rate, activity and body temperature in rainbow trout (Oncorhynchus mykiss) swimming freely amongst ~5000 conspecifics in a sea cage. Our findings clearly demonstrate that while both acute aquaculture-related stress and spontaneous activity resulted in transient reductions in GBF (i.e. reductions of up to 65%), recovery from stressful handling practices subsequently involved a substantial and prolonged gastrointestinal hyperemia far beyond the level observed prior to the stressor. The gastrointestinal hyperemia may be necessary to repair the damage to the gastrointestinal tract caused by acute stress. Furthermore, heart rate responses to acute stress or voluntary activity differed depending on the individual’s physiological state. Stressed fish (i.e. mean heart rates >70 beats min−1) exhibited a bradycardic response to acute stress or activity, whereas fish with mean heart rates <60 beats min−1 instead demonstrated strong tachycardic responses. Remote monitoring of physiological and behavioural variables using bio-loggers can provide unique insights into ‘real-life’ responses of animals, which can largely differ from the responses observed in confined laboratory settings. © 2019, The Author(s).
|
|
| 26. |
- Brijs, Jeroen, et al.
(författare)
-
The final countdown: Continuous physiological welfare evaluation of farmed fish during common aquaculture practices before and during harvest
- 2018
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 495, s. 903-911
-
Tidskriftsartikel (refereegranskat)abstract
- Welfare of farmed fish has become of increasing concern for consumers, producers, interest groups and authorities. To improve fish welfare, it is necessary to find indicators that can identify stressful situations early enough so that an intervention can take place before detrimental effects occur. By using heart rate bio-loggers in freely swimming rainbow trout (Oncorhynchus mykiss), combined with plasma cortisol levels and a range of haematological and blood chemistry parameters, we assessed the severity of stress responses induced by a range of common aquaculture practices before and during harvest. Following surgery, transportation and reintroduction with conspecifics in the sea cage, it took similar to 4 days for heart rate to stabilize and for a clear circadian rhythm in heart rate to emerge (i.e. average circadian fluctuation in heart rate of similar to 25 to 27 beats min(-1)). The presence or absence of this circadian rhythm in heart rate could inform researchers in the aquaculture industry whether or not specific farming routines induce unnecessary and prolonged stress. The elevations in heart rate caused by common farming practises such as crowding and transportation (e.g. heart rate increased by similar to 8 and 9 beats min-1 above what would normally be expected for that time of day, respectively) corresponded well with increases in plasma cortisol levels. Stressful farming practises or events (indicated by elevated plasma cortisol levels) such as air exposure during brailing and aquatic hypoxia triggered a hypoxic bradycardia until fish were released back into oxygenated water whereupon heart rate significantly increased to repay the accumulated oxygen debt. Repeated stress induced by multiple farming practises (i.e. combined stressors of crowding, brailing and transportation) clearly had a cumulative and long-lasting effect as heart rate peaked at similar to 25 beats min(-1) above what would normally be expected for that time of day. Heart rate also remained significantly elevated by similar to 9 beats min(-1) the following morning, suggesting that if rainbow trout need to be subjected to multiple stressors during consequtive days, it is recommended that sufficient time for recovery is provided between stressors. This study demonstrates that heart rate monitoring can be useful to assess stress levels of freely swimming fish in sea cages. Moreover, the use of implantable bio-loggers opens up a broad range of possible applications that will allow researchers to investigate the effects of environmental and/or anthropogenic stressors on the welfare of fish under conditions more realistic to the aquaculture industry.
|
|
| 27. |
- Chen, Deliang, 1961, et al.
(författare)
-
Summary of a workshop on extreme weather events in a warming world organized by the Royal Swedish Academy of Sciences
- 2020
-
Ingår i: Tellus Series B-Chemical and Physical Meteorology. - : Stockholm University Press. - 1600-0889 .- 0280-6509. ; 72:1
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change is not only about changes in means of climatic variables such as temperature, precipitation and wind, but also their extreme values which are of critical importance to human society and ecosystems. To inspire the Swedish climate research community and to promote assessments of international research on past and future changes in extreme weather events against the global climate change background, the Earth Science Class of the Royal Swedish Academy of Sciences organized a workshop entitled 'Extreme weather events in a warming world' in 2019. This article summarizes and synthesizes the key points from the presentations and discussions of the workshop on changes in floods, droughts, heat waves, as well as on tropical cyclones and extratropical storms. In addition to reviewing past achievements in these research fields and identifying research gaps with a focus on Sweden, future challenges and opportunities for the Swedish climate research community are highlighted.
|
|
| 28. |
|
|
| 29. |
- Gogoi, Neeha, et al.
(författare)
-
Silyl-Functionalized Electrolyte Additives and Their Reactivitytoward Lewis Bases in Li-Ion Cells br
- 2022
-
Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 34:8, s. 3831-3838
-
Tidskriftsartikel (refereegranskat)abstract
- Silyl groups are included in a wide range of electrolyteadditives to enhance the performance of state-of-the-art Li-ion batteries. Arecognized representative thereof is tris-(trimethylsilyl)phosphate(TMSPa) which, along with the similarly structured phosphite, has beenat the center of numerous electrolyte studies. Even though the silyl grouphas already been widely reported to be specifically reactive towardsfluorides, herein, a reactivity towards several Lewis bases typically found inLi-ion cells is postulated and investigated with the aim to establish a moresimplified and generally applicable reaction mechanism thereof. Bothgaseous and electrolyte soluble reactants and products are monitored bycombining nuclear magnetic resonance and injection cell-coupled massspectrometry. Experimental observations are supported by computationalmodels. The results clearly demonstrate that the silyl groups react withwater, hydroxide, and methoxide and thereby detach in a stepwise fashion from the central phosphate in TMSPa. Intermolecularinteraction between TMSPa and the reactants likely facilitates dissolution and lowers the free energy of reaction. Lewis bases are wellknown to trigger side reactions involving both the Li-ion electrode and electrolyte. By effectively scavenging these, the silyl group canbe explained to lower cell impedance and prolong the lifetime of modern Li-ion batteries.
|
|
| 30. |
- Hjelmstedt, P., et al.
(författare)
-
Assessing the effectiveness of percussive and electrical stunning in rainbow trout: Does an epileptic-like seizure imply brain failure?
- 2022
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 552
-
Tidskriftsartikel (refereegranskat)abstract
- Both percussive and electrical stunning have been highlighted as methods that can be used to quickly render fish unconscious before being killed. However, accurately assessing unconsciousness in animals following stunning remains challenging, and thus methods for reliable interpretation and validation of different stunning methods are urgently needed. Here, we used a non-invasive technique to continuously record electroencephalograms (EEG) of rainbow trout (Oncorhynchus mykiss) enabling us to compare the effects of both percussive stunning, using a captive bolt gun, and various combinations of electrical stun parameters delivered in water. The EEG signals were assessed for the absence or presence of an epileptic-like seizure and for visually evoked responses (VERs). No epileptic-like seizures or VERs were observed after captive bolt stunning. We found that it is possible to reliably induce an epileptic-like seizure and an immediate, but short lasting, loss of VERs following a 1 s exposure to an electrical field strength of at least 2.8 VRMS cm−1 and current density of 0.22 ARMS dm−2 in water of conductivity of ~1000 μS cm−1 using a 50 Hz AC current. However, to avoid recovery of VERs shortly after the stun, it was necessary to increase the duration of the stun application (≥30 s), the electrical field strength (10.2 VRMS cm−1) and the current density (0.84 ARMS dm−2 respectively). We found no clear relationship between presence and absence of ventilation and VERs following electrical stunning in rainbow trout, highlighting that loss of ventilation may not be a good indicator of brain failure in rainbow trout. Our results clearly show that the presence of an epileptic-like seizure following an electrical stun does not guarantee a prolonged period where the fish is unresponsive to visual stimulation (i.e. absence of VERs). It was further found that VERs can return before the end of the seizure. As both presence of a seizure and absence of VERs have been used independently as indicators of unconsciousness in fish, we emphasize the necessity to carefully consider and evaluate the reliability of neurophysiological indicators of unconsciousness when validating methods to stun fish. © 2022
|
|
| 31. |
- Hjelmstedt, P., et al.
(författare)
-
Continuous physiological welfare evaluation of European whitefish (Coregonus lavaretus) during common aquaculture practices leading up to slaughter
- 2021
-
Ingår i: Aquaculture. - : Elsevier BV. - 0044-8486 .- 1873-5622. ; 534
-
Tidskriftsartikel (refereegranskat)abstract
- European whitefish (Coregonus lavaretus) is an aquaculture species with the potential for expanded cultivation in the fresh and brackish waters of Northern Europe. Yet, relatively little species-specific information is available regarding the stress responses and associated welfare implications for this species in captivity. We addressed this knowledge gap by using a combination of implantable heart rate bio-loggers and a range of traditional stress indicators (e.g. haematological parameters and plasma concentrations of cortisol, glucose and ions) to comprehensively evaluate the physiological responses of freely swimming whitefish in captivity, as well as when subjected to aquaculture practices and stressors that commonly occur prior to and during slaughter. Whitefish appeared to recover rapidly from surgery, as resting heart rate decreased within 36 h to stabilize at similar to 25 beats min(-1) for the next 18 days when fish were left relatively undisturbed (i.e. personnel were only present when feeding fish). In contrast with previous studies on farmed rainbow trout and Atlantic salmon, whitefish did not exhibit a clear circadian heart rate rhythm, which may be related to species-specific differences in diurnal locomotor activity. Whitefish also appear to have a well-developed capacity for thermal acclimation of heart rate, as daily resting heart rate did not change during the undisturbed period despite an increase in body temperature from similar to 6.8 to 11.2 degrees C. Following acute stressors such as crowding and transportation, the physiological response of whitefish typically involved transient elevations in heart rate, plasma cortisol and glucose, and red blood cell swelling, while plasma [K+] decreased. In contrast, the heart rate of whitefish plummeted following the combination of brailing (i.e. to haul in fish with a brail/net) and CO2 exposure prior to slaughter, while plasma cortisol, glucose and [Ca2+] significantly increased. An unforeseen finding concerns the substantial and long-lasting physiological stress response observed in whitefish when held in close proximity (i.e. within similar to 10 m) to a rainbow trout net pen, as the mean heart rate of whitefish increased from similar to 32 to 43 beats min(-1) (i.e. an increase of similar to 34%). This may represent an innate physiological response to the threat of predation, which consequently increases the allostatic load and energetic expenditure of whitefish when farmed alongside salmonids. To conclude, this study highlights the importance of performing long-term, species-specific evaluations of freely swimming fish in real aquaculture settings, and provides a platform for further research aiming to determine the welfare implications of simultaneously farming predatory and prey species in close proximity.
|
|
| 32. |
- Hjelmstedt, P., et al.
(författare)
-
Effects of prophylactic antibiotic-treatment on post-surgical recovery following intraperitoneal bio-logger implantation in rainbow trout
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Bio-logging devices can provide unique insights on the life of freely moving animals. However, implanting these devices often requires invasive surgery that causes stress and physiological side-effects. While certain medications in connection to surgeries have therapeutic capacity, others may have aversive effects. Here, we hypothesized that the commonly prescribed prophylactic treatment with enrofloxacin would increase the physiological recovery rate and reduce the presence of systemic inflammation following the intraperitoneal implantation of a heart rate bio-logger in rainbow trout (Oncorhynchus mykiss). To assess post-surgical recovery, heart rate was recorded for 21 days in trout with or without enrofloxacin treatment. Contrary to our hypothesis, treated trout exhibited a prolonged recovery time and elevated resting heart rates during the first week of post-surgical recovery compared to untreated trout. In addition, an upregulated mRNA expression of TNFα in treated trout indicate a possible inflammatory response 21 days post-surgery. Interestingly, the experience level of the surgeon was observed to have a long-lasting impact on heart rate. In conclusion, our study showed no favorable effects of enrofloxacin treatment. Our findings highlight the importance of adequate post-surgical recovery times and surgical training with regards to improving the welfare of experimental animals and reliability of research outcomes. © 2020, The Author(s).
|
|
| 33. |
- Jansson, Desirée, et al.
(författare)
-
Intestinal spirochaetes (genus Brachyspira) colonise wild birds in the southern Atlantic region and Antarctica
- 2015
-
Ingår i: Infection Ecology & Epidemiology. - : Informa UK Limited. - 2000-8686. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The genus Brachyspira contains well-known enteric pathogens of veterinary significance, suggested agents of colonic disease in humans, and one potentially zoonotic agent. There are recent studies showing that Brachyspira are more widespread in the wildlife community than previously thought. There are no records of this genus in wildlife from the southern Atlantic region and Antarctica. Our aim was therefore, to determine whether intestinal spirochaetes of genus Brachyspira colonise marine and coastal birds in this region.METHOD: Faecal samples were collected from marine and coastal birds in the southern Atlantic region, including sub-Antarctic islands and Antarctica, in 2002, 2009, and 2012, with the aim to isolate and characterise zoonotic agents. In total, 205 samples from 11 bird species were selectively cultured for intestinal spirochaetes of genus Brachyspira. To identify isolates to species level, they were subjected to phenotyping, species-specific polymerase chain reactions, sequencing of partial 16S rRNA, NADH oxidase (nox), and tlyA genes, and phylogenetic analysis. Antimicrobial susceptibility tests were performed.RESULTS: Fourteen unique strains were obtained from 10 birds of three species: four snowy sheathbills (Chionis albus), three kelp geese (Chloephaga hybrida subsp. malvinarum), and three brown skua (Stercorarius antarcticus subsp. lonnbergi) sampled on the Falkland Islands, Tierra del Fuego in Argentina, South Georgia, South Shetland Islands, and the Antarctic Peninsula. Five Brachyspira strains were closely related to potentially enteropathogenic Brachyspira sp. of chickens: B. intermedia (n=2, from snowy sheathbills), and B. alvinipulli (n=3, from a kelp goose and two snowy sheathbills). Three strains from kelp geese were most similar to the presumed non-pathogenic species 'B. pulli' and B. murdochii, whereas the remaining six strains could not be attributed to currently known species. No isolates related to human strains were found. None of the tested strains showed decreased susceptibility to tiamulin, valnemulin, doxycycline, tylvalosin, lincomycin, or tylosin.CONCLUSIONS: This is the first report of intestinal spirochaetes from this region. Despite limitations of current diagnostic methods, our results, together with earlier studies, show that Brachyspira spp., including potentially pathogenic strains, occur globally among free-living avian hosts, and that this genus encompasses a higher degree of biodiversity than previously recognised.
|
|
| 34. |
- Johansson, Sofia, et al.
(författare)
-
High frequency vertical InAs nanowire MOSFETs integrated on Si substrates
- 2012
-
Ingår i: Physica Status Solidi. C, Current Topics in Solid State Physics. - : Wiley. - 1610-1634. ; 9:2, s. 350-353
-
Tidskriftsartikel (refereegranskat)abstract
- RF and DC characterization of vertical InAs nanowire MOSFET on Si substrates are presented. Nanowire arrays are epitaxially integrated on Si substrates by use of a thin InAs buffer layer. For device fabrication, high-k HfO2 gate dielectric and wrap-gates are used. Post-deposition annealing of the high-k is evaluated by comparing one annealed and one not-annealed sample. The annealed sample show better DC characteristics in terms of transconductance, g(m) = 155 mS/mm, and on-current, I-on = 550 mA/mm. Box plots of on-current, on-resistance and transconductance for all 190-nanowire-array transistors on the annealed sample suggest that the electrical properties of the nanowires are preserved when scaling the nanowire diameter. Finally, high frequency characterisation yields a unity current gain cut-off frequency of f(t) = 9.3 GHz for the annealed sample and f(t) = 2.0 GHz for the not-annealed sample. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
|
|
| 35. |
- Johansson, Sofia, et al.
(författare)
-
RF Characterization of Vertical InAs Nanowire Wrap-Gate Transistors Integrated on Si Substrates
- 2011
-
Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480. ; 59:10, s. 2733-2738
-
Tidskriftsartikel (refereegranskat)abstract
- We present dc and RF characterization of InAs nanowire field-effect transistors (FETs) heterogeneously integrated on Si substrates in a geometry suitable for circuit applications. The FET consists of an array of 182 vertical InAs nanowires with about 6-nm HfO high-gate dielectric and a wrap-gate length of 250 nm. The transistor has a transconductance of 155 mS/mm and an on-current of 550 mA/mm at a gate voltage of 1.5 V and a drain voltage of 1 V. S-parameter measurements yield an extrinsic cutoff frequency of 9.3 GHz and a extrinsic maximum oscillation frequency of 14.3 GHz.
|
|
| 36. |
|
|
| 37. |
- Lindahl, Cecilia, et al.
(författare)
-
Responses of Pigs to Stunning with Nitrogen Filled High-Expansion Foam
- 2020
-
Ingår i: Animals. - : MDPI AG. - 2076-2615. ; 10:12, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- Nitrogen gas (N2) delivered in high expansion foam in a closed container could be a feasible method for humanely stunning pigs. This study aimed to evaluate potential aversion in pigs to the N2 foam method and its effect on stun quality. Furthermore, the study aimed to assess potential aversion to the foam itself. Sixty pigs (27.8 ± 4.4 kg) were divided into three treatments and were exposed to either N2-filled foam, air-filled foam, or no foam air. The N2 foam was effective at purging the air from the container and quickly created stable anoxic conditions. The pigs did not show any strong aversive behaviours when exposed to foam. However, they seemed to avoid putting their heads and snouts into the foam when foam levels became high. Escape attempts through the lid also increased when the foam started covering their heads. The mean time to loss of posture was 57.9 s. Based on the results, stunning with the N2 foam technique could be a viable alternative to high concentration CO2 stunning and potentially lead to improved animal welfare at slaughter.
|
|
| 38. |
- Persson, Erik, et al.
(författare)
-
Cultural Relict Plants in the Nordic Region
- 2014
-
Ingår i: Sources to the history of gardening : Four interdisciplinary seminars 2010-2013 arranged by the Nordic Network for the Archaeology and Archaeobotany of Gardening - Four interdisciplinary seminars 2010-2013 arranged by the Nordic Network for the Archaeology and Archaeobotany of Gardening. - 9789187117862 ; 2014:25, s. 299-312
-
Bokkapitel (refereegranskat)
|
|
| 39. |
- Persson, Erik, et al.
(författare)
-
What’s in a name? : Exploring the definition of ‘Cultural Relict Plant’
- 2014
-
Ingår i: Sources to the history of gardening : Four Interdisciplinary Seminars 2010–2013 Arranged By the Nordic Network for the Archaeology and Archaeobotany of Gardening (NTAA) - Four Interdisciplinary Seminars 2010–2013 Arranged By the Nordic Network for the Archaeology and Archaeobotany of Gardening (NTAA). - 9789187117862 ; 2014:25, s. 289-298
-
Bokkapitel (refereegranskat)
|
|
| 40. |
- Persson, Karl-Magnus, et al.
(författare)
-
1/f-noise in Vertical InAs Nanowire Transistors
- 2013
-
Ingår i: 2013 International Conference on Indium Phosphide and Related Materials (IPRM). - 1092-8669. ; , s. 1-2
-
Konferensbidrag (refereegranskat)abstract
- The material quality at high-k interfaces are a major concern for FET devices. We study the effect on two types of InAs nanowire (NW) transistors and compare their characteristics. It is found that by introducing an inner layer of Al2O3 at the high-kappa interface, the low frequency noise (LFN) performance regarding gate voltage noise spectral density, S-Vg, is improved by one order of magnitude per unit gate area.
|
|
| 41. |
- Persson, Karl-Magnus, et al.
(författare)
-
Extrinsic and Intrinsic Performance of Vertical InAs Nanowire MOSFETs on Si Substrates
- 2013
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383. ; 60:9, s. 2761-2767
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents DC and RF characterization as well as modeling of vertical InAs nanowire MOSFETs with LG = 200 nm and Al2O3/HfO2 high-κ dielectric. Measurements at VDS = 0.5 V show that high transconductance (gm = 1.37 mS/μm), high drive current (IDS = 1.34 mA/μm), and low on-resistance (RON = 287 Ωμm) can be realized using vertical InAs nanowires on Si substrates. By measuring the 1/f-noise, the gate area normalized gate voltage noise spectral density, SVG·LG·WG, is determined to be lowered one order of magnitude compared to similar devices with a high-κ film consisting of HfO2 only. Additionally, with a virtual source model we are able to determine the intrinsic transport properties. These devices (LG = 200 nm) show a high injection velocity (vinj = 1.7·107 cm/s) with a performance degradation for array FETs predominantly due to an increase in series resistance.
|
|
| 42. |
- Persson, Karl-Magnus, et al.
(författare)
-
InAs nanowire MOSFET differential active mixer on Si-substrate
- 2014
-
Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 50:9, s. 682-682
-
Tidskriftsartikel (refereegranskat)abstract
- An active single balanced down-conversion mixer is implemented using InAs nanowire metal oxide semiconductor field effect transistors (MOSFETs) as both active devices and passive resistive loads. Circuits with 6 dB low-frequency voltage gain and a 3 dB bandwidth of 2 GHz are measured for a DC power consumption of 3.8 mW from a 1.5 V supply. The circuits are fabricated using contacts made with 12 μmline- width optical lithography.
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
- Sandberg, Christer, et al.
(författare)
-
Effects of chip pretreatment and feeding segments on specific energy and pulp quality in TMP production
- 2018
-
Ingår i: Nordic Pulp & Paper Research Journal. - : Walter de Gruyter GmbH. - 0283-2631 .- 2000-0669. ; 33:3, s. 448-459
-
Tidskriftsartikel (refereegranskat)abstract
- Increased wood softening and refining intensity have earlier been utilized to improve refining efficiency in mechanical pulping. We have evaluated a combination of increased softening by low dose sulphite chip pretreatment and increased intensity by feeding segment design in a TMP line for production of high quality printing papers. Norway spruce wood chips were preheated, compressed in an Impressafiner and impregnated with water or sodium sulphite solutions (Na2SO3 charges 3.6 and 7.2 kg/t). Chips were refined in two parallel 68" double disc refiners using two different refining conditions: standard bidirectional segments at normal production rate (9 t/h) and feeding segments at increased production rate (11.1-12.1 t/h). The feeding segments enabled a 30 % increase in production rate. Refining with feeding segments at 12.1 t/h production rate combined with chip pretreatment with 3.6 kg/t sodium sulphite reduced the specific energy 360 kWh/t (19 %) compared to refining with standard segments and no pretreatment. Pulp properties were similar for the two configurations. The combination of feeding segments and chip pretreatment with water reduced the specific energy 180 kWh/t (9 %). Implementation of most of the technology presented has reduced the electrical energy use for the mill by approximately 80 GWh/year.
|
|
| 46. |
- Sundh, Henrik, 1976, et al.
(författare)
-
Effects of coeliacomesenteric blood flow reduction on intestinal barrier function in rainbow trout Oncorhynchus mykiss
- 2018
-
Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 93:3, s. 519-527
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the current work was to elucidate if there is a connection between stress-induced decrease in coeliacomesenteric artery blood flow (i.e. gastrointestinal blood flow; GBF) and disruption of the intestinal primary barrier in rainbow trout Oncorhynchus mykiss. Upon initiation of a 15 min acute chasing stress, the GBF decreased instantly by c. 92%. The GBF then slowly increased and reached c. 28% of resting values at the end of the stress protocol. After the stress was ceased, the GBF slowly increased and returned to resting values within c. 45 min. Intestinal permeability assessment in an Ussing-chambers set-up revealed impaired intestinal barrier function 24 h after stress. When the stress-induced GBF reduction was mimicked by an experimental occlusion of the coeliacomesenteric artery for 15 min followed by 24 h recovery, no effect on intestinal barrier function was observed. These results suggest that no direct causal relationship can be found between the GBF reduction and development of intestinal barrier dysfunction following periods of acute stress in this species of fish.
|
|
| 47. |
- van den Berg, Emma, et al.
(författare)
-
Profiling amyloid-β peptides as biomarkers for cerebral amyloid angiopathy
- 2024
-
Ingår i: JOURNAL OF NEUROCHEMISTRY. - 0022-3042 .- 1471-4159.
-
Tidskriftsartikel (refereegranskat)abstract
- Brain amyloid-beta (A beta) deposits are key pathological hallmarks of both cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD). Microvascular deposits in CAA mainly consist of the A beta(40) peptide, whereas A beta(42) is the predominant variant in parenchymal plaques in AD. The relevance in pathogenesis and diagnostic accuracy of various other A beta isoforms in CAA remain understudied. We aimed to investigate the biomarker potential of various A beta isoforms in cerebrospinal fluid (CSF) to differentiate CAA from AD pathology. We included 25 patients with probable CAA, 50 subjects with a CSF profile indicative of AD pathology (AD-like), and 23 age- and sex-matched controls. CSF levels of A beta(1-34), A beta(1-37), A beta(1-38), A beta(1-39), A beta(1-40), and A beta(1-42) were quantified by liquid chromatography mass spectrometry. Lower CSF levels of all six A beta peptides were observed in CAA patients compared with controls (p = 0.0005-0.03). Except for A beta(1-42) (p = 1.0), all peptides were decreased in CAA compared with AD-like subjects (p = 0.007-0.03). Besides A beta(1-42), none of the A beta peptides were decreased in AD-like subjects compared with controls. All A beta peptides combined differentiated CAA from AD-like subjects better (area under the curve [AUC] 0.84) than individual peptide levels (AUC 0.51-0.75). Without A beta(1-42) in the model (since decreased A beta(1-42) served as AD-like selection criterion), the AUC was 0.78 for distinguishing CAA from AD-like subjects. CAA patients and AD-like subjects showed distinct disease-specific CSF A beta profiles. Peptides shorter than A beta(1-42) were decreased in CAA patients, but not AD-like subjects, which could suggest different pathological mechanisms between vascular and parenchymal A beta accumulation. This study supports the potential use of this panel of CSF A beta peptides to indicate presence of CAA pathology with high accuracy.
|
|
| 48. |
|
|
| 49. |
- Wu, Jun, et al.
(författare)
-
RF Characterization of Vertical Wrap-Gated InAs/High-κ Nanowire Capacitors
- 2016
-
Ingår i: IEEE Transactions on Electron Devices. - 0018-9383. ; 63:2, s. 584-589
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents RF as well as low-frequency capacitance–voltage (C–V) characterization of vertical wrap-gated InAs/high-κ nanowire MOS capacitors. A full equivalent circuit model for traps is used to fit the low-frequency C–V characteristics, from which the interface trap density (Dit) and border trap density (Nbt) are evaluated separately. The results show comparable Nbt but far lower Dit (<10E12 eV−1cm−2 near the conduction band edge) for a nanowire MOS gate-stack compared with planar references. In the RF domain, the influence of nanowire series resistances become significant, and by introducing a distributed RC-model, the nanowire resistivity (ρnw) is evaluated from the capacitance data as a function of the gate bias. An ON/OFF ρnw ratio of 10E−2 is obtained for the best device. Using the measured data, the quality factor is finally evaluated both for fabricated and ideal capacitors. The results agree well with simulated data.
|
|
| 50. |
|
|
