| 1. |
- Andersson, Mathias H., et al.
(författare)
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Displacement effects of ship noise on fish population : FP7 - Collaborative Project n° 314227 WP 4: Sensitivity of marine life to shipping noise Task 4.2.1
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Ship induced noise is one of the major contributors to the elevated noise levels in the world’s oceans today. However, the knowledge about the impact on marine organisms is still scarce. Especially the effects on fish behaviour needs to be studied as fish are a fundamental part of the oceans ecosystem. Direct measurement of fish behaviour in the open sea area is technically difficult but needs to be done in order to estimate reaction thresholds and scales of any reaction. This experiment studies the long term behavioural reaction by wild cod (Gadus morhua) to ship noise and describes the character and scale of the reaction. This study took place on the Swedish west coast with a small local cod population and the area is normally without any large vessel traffic. For the ship disturbance, the Swedish Coast Guard ship KBV 032 was hired and passed thru the area nine times during three days. During the three days of ship noise exposure, the noise levels increased well above the ambient noise. The ship signature was what could be expected in terms of spectral level with most radiated noise energy between 100 - 500 Hz. The ship had a higher source level than expected (232 dB re 1μPa at 1 m, 10 - 300 Hz) but this was deliberate as the crew was asked to use the propellers in a non-optimal way to generate as much noise as possible. The result was a lot of broadband cavitation pulses generated by the ship. Then a noise footprint model was created and used in the estimates of received levels (exposure level) by the individual fish in the area based on the most probable location. It was clear in the transmission loss varied between the two sites where at the shallow site, the noise was attenuated more compared to the deep site. This is probably caused by the quite complicated propagation pattern. Also, the acoustically different bottom properties will affect the transmission loss in the area. In total, 39 cod (Gadus morhua) were caught by hand jigging and were fitted with internal acoustical tags. Bottom mounted receivers were deployed covering the area where the cod were known to inhabit. This study was designed to capture more large scale movements of hundreds of meters and not startle responses to the ship noise. Out of the 39 tagged fish, 17 and 18 fish met the set quality criterion for the short time behaviour analysis and 23 fish for long time behaviour to be included in the analysis. Some fish met the quality criteria for both the short and long term analysis. The other fish were either eaten by seals, caught by fishermen, left the area or had a malfunctioning tag. In general, the noticed reaction in terms of horizontal swimming were much smaller than expected and what the study was designed for. This results was surprising as the sound pressure levels the fish were exposed to would, based on the literature, cause a strong behaviour response in the fish. The movement was not in any large scale that would affect their energy consumption and affect their long term survival. This study was able to track fish with an accuracy of less than 10 m and estimates an interval of received noise level. This is one of the first studies of its kind that is tracking free swimming fish over a long period of time during an acoustic disturbance.
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| 2. |
- Blom, Kristin, et al.
(författare)
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Eosinophil associated genes in the inflammatory bowel disease 4 region : Correlation to inflammatory bowel disease revealed
- 2012
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Ingår i: World Journal of Gastroenterology. - : Baishideng Publishing Group Inc.. - 1007-9327 .- 2219-2840. ; 18:44, s. 6409-6419
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To study the association between inflammatory bowel disease (IBD) and genetic variations in eosinophil protein X (EPX) and eosinophil cationic protein (ECP). METHODS: DNA was extracted from ethylene diamine tetraacetic acid blood of 587 patients with Crohn's disease (CD), 592 with ulcerative colitis (UC) and 300 healthy subjects. The EPX405 (G > C, rs2013109), ECP434 (G > C, rs2073342) and ECP562 (G > C, rs2233860) gene polymorphisms were analysed, by the 5'-nuclease allelic discrimination assay. For determination of intracellular content of EPX and ECP in granulocytes, 39 blood samples was collected and extracted with a buffer containing cetyltrimethylammonium bromide. The intracellular content of EPX was analysed using an enzyme-linked immunosorbent assay. The intracellular content of ECP was analysed with the UniCAP (R) system as described by the manufacturer. Statistical tests for calculations of results were chi(2) test, Fisher's exact test, ANOVA, Student-Newman-Keuls test, and Kaplan-Meier survival curve with Log-rank test for trend, the probability values of P < 0.05 were considered statistically significant. RESULTS: The genotype frequency for males with UC and with an age of disease onset of >= 45 years (n = 57) was for ECP434 and ECP562, GG = 37%, GC = 60%, CC = 4% and GG = 51%, GC = 49%, CC = 0% respectively. This was significantly different from the healthy subject's genotype frequencies of ECP434 (GG = 57%, GC = 38%, CC = 5%; P = 0.010) and ECP562 (GG = 68%, GC = 29 /0,CC = 3%; P = 0.009). The genotype frequencies for females, with an age of disease onset of >= 45 years with CD (n = 62), was for the ECP434 and ECP562 genotypes GG = 37%, GC = 52%, CC = 11% and GG = 48%, GC = 47% and CC = 5% respectively. This was also statistically different from healthy controls for both ECP434 (P = 0.010) and ECP562 (P = 0.013). The intracellular protein concentration of EPX and ECP was calculated in mu g/10(6) eosinophils and then correlated to the EPX 405 genotypes. The protein content of EPX was highest in the patients with the CC genotype of EPX405 (GG = 4.65, GC = 5.93, and CC = 6.57) and for ECP in the patients with the GG genotype of EPX405 (GG = 2.70, GC = 2.47 and CC = 1.90). ANOVA test demonstrated a difference in intracellular protein content for EPX (P = 0.009) and ECP (P = 0.022). The age of disease onset was linked to haplotypes of the EPX405, ECP434 and ECP562 genotypes. Kaplan Maier curve showed a difference between haplotype distributions for the females with CD (P = 0.003). The highest age of disease onset was seen in females with the EPX405CC, ECP434GC, ECP562CC haplotype (34 years) and the lowest in females with the EPX405GC, ECP434GC, ECP562GG haplotype (21 years). For males with UC there was also a difference between the highest and lowest age of the disease onset (EPX405CC, ECP434CC, ECP562CC, mean 24 years vs EPX405GC, ECP434GC, ECP562GG, mean 34 years, P = 0.0009). The relative risk for UC patients with ECP434 or ECP562-GC/CC genotypes to develop dysplasia/cancer was 2.5 (95%CI: 1.2-5.4, P = 0.01) and 2.5 (95%CI: 1.1-5.4, P = 0.02) respectively, compared to patients carrying the GG-genotypes. CONCLUSION: Polymorphisms of EPX and ECP are associated to IBD in an age and gender dependent manner, suggesting an essential role of eosinophils in the pathophysiology of IBD.
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| 3. |
- Blom, Peter, et al.
(författare)
-
A non-linear constitutive audio frequency magneto-sensitive rubber model including amplitude, frequency and magnetic field dependence.
- 2011
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Ingår i: Journal of Sound and Vibration. - : Elsevier. - 0022-460X .- 1095-8568. ; 330:5, s. 947-954
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Tidskriftsartikel (refereegranskat)abstract
- A novel constitutive model of magneto-sensitive rubber in the audible frequency range is presented. Characteristics inherent to magneto-sensitive rubber within this dynamic regime are defined: magnetic sensitivity, amplitude dependence, elasticity and viscoelasticity. Prior to creating the model assumptions based on experimental observations concerning these components are formulated. The first observation is that not only does the rubber display a strong amplitude dependence even for small strains, but also the magnetic sensitivity is strongly amplitude dependent. The second and third are, respectively, that the elastic component is magneto-sensitive, whereas the viscoelastic dependence on magnetic induction appears to be small. Thus, the model is developed from these assumptions and parameters are optimized with respect to experimental values for one case and subsequently validated for others; a very good agreement is obtained.
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| 4. |
- Blom, Peter, et al.
(författare)
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Amplitude and frequency dependence of magneto-sensitive rubber in a wide frequency range
- 2005
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Ingår i: Polymer testing. - : Elsevier. - 0142-9418 .- 1873-2348. ; 24:5, s. 656-662
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Tidskriftsartikel (refereegranskat)abstract
- Two new aspects of the dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber are highlighted: the existence of an amplitude dependence of the shear modulus - referred to as the Fletcher-Gent effect - for even small displacements, and the appearance of large MS effects. In order to illustrate these two features, results are presented of measurements performed in the audible frequency range on two different kinds of rubber: silicone and natural rubber with a respective iron particle volume concentration of 33%. The particles used are of irregular shape and randomly distributed within the rubber. An external magnetic field of 0-0.8 T is applied. Both kinds of rubber are found to be strongly amplitude dependent and, furthermore, displaying large responses to externally applied magnetic fields - a maximum of 115%. Also included are graphs of measurements on silicone and natural rubber devoid of iron particles. Those results support the conclusion that introducing iron particles in the rubber gives rise to a strong, non-negligible, amplitude dependence in the entire frequency range.
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| 5. |
- Blom, Peter, 1979-
(författare)
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Exploring the vibration control potential of magneto-sensitive rubber
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two new aspects of the dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber are highlighted: the existence of an amplitude dependence of the shear modulus—referred to as the Fletcher–Gent effect—for even small displacements, and the appearance of large MS effects. These results have been obtained experimentally and are subsequently used to model two examples of magneto-sensitive rubber isolators to show how by means of MS rubber they can be improved. The first model calculates the transfer stiffness of a torsionally excited isolator and the second one the energy flow into the foundation for a bushing inserted between a vibrating mass and an infinite plate. In both examples notable improvements in isolation can be obtained
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| 6. |
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| 7. |
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| 8. |
- Blom, Peter, 1979-
(författare)
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Magneto-sensitive rubber in the audible frequency range
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber is the focus of this thesis consisting of five papers A-E. Paper A presents results drawn from experiments on samples subjected to different constant shear strains over varying frequencies and magnetic fields. Main features observed are the existence of an amplitude dependence of the shear modulus referred to as the Fletcher-Gent effect for even small displacements, and the appearance of large MS effects. These results are subsequently used in Paper B and C to model two magneto-sensitive rubber isolators, serving to demonstrate how, effectively, by means of MS rubber, these can be readily improved. The first model calculates the transfer stiffness of a torsionally excited isolator, and the second one, the energy flow into the foundation for a bushing inserted between a vibrating mass and an infinite plate. In both examples, notable improvements in isolation are obtainable. Paper D presents a non-linear constitutive model of MS rubber in the audible frequency range. Characteristics inherent to magneto-sensitive rubber within this dynamic regime are defined: magnetic sensitivity, amplitude dependence, elasticity and viscoelasticity. A very good agreement with experimental values is obtained. In Paper E, the magneto-sensitive rubber bushing stiffness for varying degrees of magnetization is predicted by incorporating the non-linear magneto-sensitive audio frequency rubber model developed in Paper D, into an effective engineering formula for the torsional stiffness of a rubber bushing. The results predict, and clearly display, the possibility of controlling over a large range through the application of a magnetic field, the magneto-sensitive rubber bushing stiffness.
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| 9. |
- Blom, Peter, et al.
(författare)
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Smart audio frequency energy flow control by magneto-sensitive rubber isolators
- 2008
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Ingår i: Smart materials and structures. - : IOP Publishing. - 0964-1726 .- 1361-665X. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- A magneto-sensitive rubber isolator inserted between a source and an infinite plate is modelled in the audible frequency range, and the energy flow into the plate with the rubber subjected to a magnetic field applied perpendicular to the axial displacement is calculated. Subsequently the result is compared to the corresponding energy flow for zero magnetic induction; upon the application of an external magnetic field the rubber becomes stiffer, thus shifting the internal resonances of the isolator. This is a fast and reversible process enabling adaption of the isolator to rapidly changing audio frequency conditions by simply turning on and off a magnetic field. In the application example considered, the energy flow into the plate at the first internal dynamic peak stiffness frequency is reduced by approximately 7 dB-a large difference in a sound and vibration context-by inducing magnetic saturation of the rubber.
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| 10. |
- Blom, Peter, et al.
(författare)
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The frequency, amplitude and magnetic field dependent torsional stiffness of a magneto-sensitive rubber bushing
- 2011
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Ingår i: International Journal of Mechanical Sciences. - : Elsevier BV. - 0020-7403 .- 1879-2162. ; 60:1, s. 54-58
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Tidskriftsartikel (refereegranskat)abstract
- A dynamic torsional stiffness model of a magneto-sensitive circular annular rubber bushing is presented where influences of frequency, amplitude and magnetic field dependence are included. This is achieved by employing a newly developed non-linear magneto-sensitive audio frequency constitutive equation in an engineering formula for the torsional stiffness of a rubber bushing. The engineering stiffness formula predicts the frequency and amplitude dependent stiffness in a simple way, based on geometric dimensions and the shear modulus. The shear modulus is provided by the rubber model. The results from these calculations predict and clearly display the possibility of controlling over a large frequency range, through the application of a magnetic field, the magneto-sensitive rubber bushing stiffness.
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| 11. |
- Gatchell, Michael, et al.
(författare)
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Commissioning of the DESIREE storage rings - a new facility for cold ion-ion collisions
- 2014
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Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488:1
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Konferensbidrag (refereegranskat)abstract
- We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C-) and smaller carbon anion molecules (C-2(-), C-3(-), C-4(-) etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat-and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.
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| 12. |
- Gatchell, Michael, et al.
(författare)
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First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE
- 2014
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Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488
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Konferensbidrag (refereegranskat)abstract
- We have stored the first beams in one of the rings of the double electrostatic ion-storage ring, DESIREE at cryogenic and at room temperature conditions. At cryogenic operations the following parameters are found. Temperature; T= 13K, pressure; p <10(-13) mbar, initial number of stored ions; N > 10(7) and storage lifetime of a C-2(-) beam; tau = 450 S.
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| 13. |
- Hartman, Henrik, et al.
(författare)
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First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
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| 14. |
- Kari, Leif, et al.
(författare)
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Constitutive model for magneto-sensitive rubber in the audible frequency range including amplitude, frequency and magnetic field dependence
- 2008
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Ingår i: CONSTITUTIVE MODELS FOR RUBBER V. - LONDON : TAYLOR & FRANCIS LTD. - 9780415454421 ; , s. 357-360
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Konferensbidrag (refereegranskat)abstract
- In presenting a non-linear constitutive model for magneto-sensitive rubber in the frequency range, the influences of dynamic amplitude, frequency and magnetic field are investigated. The model is based on a non-linear, smooth Coulomb friction and fractional derivative model with parametric magnetic field dependence. Very good agreement between model and measurement results are obtained throughout the whole magnetic field, amplitude and frequency range considered.
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| 15. |
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| 16. |
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| 17. |
- Kari, Leif, et al.
(författare)
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Magneto-sensitive rubber in a noise reduction context : exploring the potential
- 2005
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Ingår i: Plastics, rubber and composites. - : Informa UK Limited. - 1465-8011 .- 1743-2898. ; 34:8, s. 365-371
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Tidskriftsartikel (refereegranskat)abstract
- In a noise reduction context, magneto-sensitive (MS) rubber is likely to become a. reality in the very near future. This conclusion is reached from the following: a review of the rapidly growing literature on the subject, a discussion around experimentally obtained data on magneto-sensitive rubber, and finally a computer simulation of a MS rubber isolator which seeks to illustrate the utility and great potential of this smart material within the audible frequency range. In contrast to normal rubber, magneto-sensitive rubber contains small iron particles that respond to externally applied magnetic fields, consequently altering the mechanical properties of the rubber. This response increases for small strains strengthening further the link to structure-borne sound applications where displacement amplitudes are usually small; this is borne out by vibration measurements in a running car engine, included for the purpose of placing experimental data on MS rubber in a real context.
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| 18. |
- Landin-Olsson, Mona, et al.
(författare)
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Immunoreactive trypsin(Ogen) in the sera of children with recent-onset insulin-dependent diabetes and matched controls
- 1990
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Ingår i: Pancreas. - : Ovid Technologies (Wolters Kluwer Health). - 0885-3177. ; 5:3, s. 241-247
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the exocrine pancreatic function at the time of diagnosis of insulin-dependent diabetes mellitus, we determined immunoreactive an-odal and cathodal trypsin(ogen) levels in sera from almost all children (n = 375) 0-14 years of age in Sweden in whom diabetes developed during 1 year, and in sex-, age-, and geographically matched control subjects (n = 312). The median level of anodal trypsin(ogen) was 5 (quartile range, 3-7) µg/L in children with newly diagnosed diabetes, compared with a median level of 7 (quartile range, 4-8) µg/L in control subjects (p < 0.0001). Similarly, the median level of cathodal trypsin(ogen) was 8 (quartile range, 4-10) µg/L in children with diabetes, compared with a median level of 11 (quartile range, 7-15) µg/L in control subjects (p < 0.0001). The median of the individual ratios between cathodal and anodal trypsin(ogen) was 1.4 in the diabetic patients and 1.7 in the control children (p < 0.001). In a multivariate test, however, only the decrease in cathodal trypsin(ogen) concentration was associated with diabetes. The levels of trypsin(ogen)s did not correlate with levels of islet cell antibodies, present in 81% of the diabetic children. Several mechanisms may explain our findings, for example, similar pathogenetic factors may affect both the endocrine and exocrine pancreas simultaneously, a failing local trophic stimulation by insulin on the exocrine cells may decrease the trypsinogen production, and there may be an increased elimination of trypsin(ogen) because of higher filtration through the kidneys in the hyperglycemic state.
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| 19. |
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| 20. |
- Mahdi, Taman, et al.
(författare)
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Secreted frizzled-related protein 4 reduces insulin secretion and is overexpressed in type 2 diabetes.
- 2012
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Ingår i: Cell Metabolism. - : Elsevier BV. - 1550-4131. ; 16:5, s. 625-633
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Tidskriftsartikel (refereegranskat)abstract
- A plethora of candidate genes have been identified for complex polygenic disorders, but the underlying disease mechanisms remain largely unknown. We explored the pathophysiology of type 2 diabetes (T2D) by analyzing global gene expression in human pancreatic islets. A group of coexpressed genes (module), enriched for interleukin-1-related genes, was associated with T2D and reduced insulin secretion. One of the module genes that was highly overexpressed in islets from T2D patients is SFRP4, which encodes secreted frizzled-related protein 4. SFRP4 expression correlated with inflammatory markers, and its release from islets was stimulated by interleukin-1β. Elevated systemic SFRP4 caused reduced glucose tolerance through decreased islet expression of Ca(2+) channels and suppressed insulin exocytosis. SFRP4 thus provides a link between islet inflammation and impaired insulin secretion. Moreover, the protein was increased in serum from T2D patients several years before the diagnosis, suggesting that SFRP4 could be a potential biomarker for islet dysfunction in T2D.
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| 21. |
- Marcus, Claude, et al.
(författare)
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Insufficient ketone body use is the cause of ketotic hypoglycemia in one of a pair of homozygotic twins
- 2007
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 92:11, s. 4080-4084
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Tidskriftsartikel (refereegranskat)abstract
- Context: Childhood ketotic hypoglycemia (KH) is a disease characterized by fasting hypoglycemia and increased levels of ketone bodies. The cause is unknown. Objective: The objective of the study was to study a pair ofhomozygotic twin boys, one of whom had severe KH from the age of 14 months, whereas the other boy was apparently healthy. Design and Results: At the age of 6 yr, the boys were thoroughly investigated. During a 24-h fasting tolerance test, the twin with KH showed hypoglycemia (blood glucose 2.0 mmol/liter) after 18 h. Three h before the occurrence of hypoglycemia, he had had 10 times higher β-hydroxybutyrate levels than his brother, who showed no signs of hypoglycemia. Their glucose production rates were normal and similar (23.3 and 21.7 μmol/kg body weight per minute in the healthy and KH twin, respectively) as well as their lipolysis rates (5.8 and 6.8 μmol/kg body weight per minute, respectively). During repeated 60-min infusions of p-hydroxybutyrate, the plasma level of /3-hydroxybutyrate increased 5-10 times more in the twin with KH (mean 1.1 mmol/liter in the healthy and 10.8 mmol/liter in the KH twin), indicating a disturbed clearance or metabolism of β-hydroxybutyrate. No mutations were found in genes involved in ketone body metabolism or transport. Conclusion: In the affected boy, KH seems to be the result of a reduced capacity to use ketone bodies, leading to increased peripheral metabolism of glucose that cannot be met by hepatic glucose production. Because the boys are homozygotic twins and only one of them is affected, the ketotic hypoglycemia is most likely caused by an altered imprinting of gene(s) involved in regulating metabolic pathways.
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| 22. |
- Nilsson, Hans-Olof, et al.
(författare)
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Effect of Cold Starvation, Acid Stress, and Nutrients on Metabolic Activity of Helicobacter pylori.
- 2002
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 68:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- Helicobacter pylori can transform, in vivo as well as in vitro, from dividing spiral-shaped forms into nonculturable coccoids, with intermediate forms called U forms. The importance of nonculturable coccoid forms of H. pylori in disease transmission and antibiotic treatment failures is unclear. Metabolic activities of actively growing as well as nonculturable H. pylori were investigated by comparing the concentrations of cellular ATP and total RNA, gene expression, presence of cytoplasmic polyphosphate granules and iron inclusions, and cellular morphology during extended broth culture and nutritional cold starvation. In addition, the effect of exposing broth-cultured or cold-starved cells to a nutrient-rich or acidic environment on the metabolic activities was investigated. ATP was detectable up to 14 days and for at least 25 days after transformation from the spiral form to the coccoid form or U form in broth-cultured and cold-starved cells, respectively. mRNAs of VacA, a 26-kDa protein, and urease A were detected by using reverse transcription-PCR in cells cultured for 2 months in broth or cold starved for at least 28 months. The ATP concentration was not affected during exposure to fresh or acidified broth, while 4- to 12-h exposures of nonculturable cells to lysed human erythrocytes increased cellular ATP 12- to 150-fold. Incubation of nonculturable cold-starved cells with an erythrocyte lysate increased total RNA expression and ureA mRNA transcription as measured by quantitative real-time reverse transcription-PCR. Furthermore, the number of structurally intact starved coccoids containing polyphosphate granules increased almost fourfold (P = 0.0022) under the same conditions. In conclusion, a specific environmental stimulus can induce ATP, polyphosphate, and RNA metabolism in nonculturable H. pylori, indicating viability of such morphological forms.
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| 23. |
- Rosén, Stefan, et al.
(författare)
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Operating a triple stack microchannel plate-phosphor assembly for single particle counting in the 12-300 K temperature range
- 2007
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics. - 0034-6748 .- 1089-7623. ; 78:11, s. 113301-
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Tidskriftsartikel (refereegranskat)abstract
- An assembly consisting of a stack of three microchannel plates (MCPs) and a phosphor screen anode has been operated over the temperature range from 300 to 12 K. We report on measurements at 6.4 kHz (using an alpha source) and with dark counts only (15 Hz). Without any particle source, the MCP bias current decreased by a factor of 2.1×103 when the temperature was lowered from 300 to 12 K. Using the alpha source, and a photomultiplier tube (PMT) to monitor the phosphor screen anode, we first observed an increase in the decay time of the phosphor from 12 to 45 μs when the temperature was decreased from 300 to 100 K while the decay time then decreased and reached a value of 5 μs at 12 K. The pulse height distribution from the PMT was measured between300 and 12 K and shows a spectrum typical for a MCP phosphor setup at 300 K and 12 K but is strongly degraded for intermediate temperatures. We conclude that the present MCP-phosphor detector assembly is well suited for position-sensitive particle counting operation at temperatures down to at least 12 K even for count rates beyond 6 kHz. This result is crucial and an important part of ongoing developments of new instrumentation for investigations of, e.g., interactions involving complex molecular ions with internal quantum state control.
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| 24. |
- Schmidt, Henning, et al.
(författare)
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DESIREE as a new tool for interstellar ion chemistry
- 2008
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Ingår i: International Journal of Astrobiology. - 1473-5504 .- 1475-3006. ; 7:3-4, s. 205-208
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Tidskriftsartikel (refereegranskat)abstract
- A novel cryogenic electrostatic storage device consisting of two ion-beam storage rings with a common straight section for studies of interactions between oppositely charged ions at low and well-defined relative velocities is under construction at Stockholm University. Here we consider the prospect of using this new tool to measure cross-sections and rate coefficients for mutual neutralization reactions of importance in interstellar ion chemistry in general and specifically in cosmic pre-biotic ion chemistry.
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| 25. |
- Thomas, Richard D., et al.
(författare)
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DESIREE : Physics with cold stored ion beams
- 2015
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Ingår i: DR2013. - : EDP Sciences. ; 84, s. 01004-01004
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Konferensbidrag (refereegranskat)abstract
- Here we will briefly describe the commissioning of the Double ElectroStatic Ion Ring ExpEriment (DESIREE) facility at Stockholm University, Sweden. This device uses purely electrostatic focussing and deflection elements and allows ion beams of opposite charge to be confined under extreme high vacuum and cryogenic conditions in separate rings and then merged over a common straight section. This apparatus allows for studies of interactions between cations and anions at very low and well-defined centre-of-mass energies (down to a few meV) and at very low internal temperatures (down to a few K).
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| 26. |
- Thomas, Richard D., et al.
(författare)
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The double electrostatic ion ring experiment : A unique cryogenic electrostatic storage ring for merged ion-beams studies
- 2011
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 82:6, s. 065112-
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Tidskriftsartikel (refereegranskat)abstract
- We describe the design of a novel type of storage device currently under construction at Stockholm University, Sweden, using purely electrostatic focussing and deflection elements, in which ion beams of opposite charges are confined under extreme high vacuum cryogenic conditions in separate rings and merged over a common straight section. The construction of this double electrostatic ion ring experiment uniquely allows for studies of interactions between cations and anions at low and well-defined internal temperatures and centre-of-mass collision energies down to about 10 K and 10 meV, respectively. Position sensitive multi-hit detector systems have been extensively tested and proven to work in cryogenic environments and these will be used to measure correlations between reaction products in, for example, electron-transfer processes. The technical advantages of using purely electrostatic ion storage devices over magnetic ones are many, but the most relevant are: electrostatic elements which are more compact and easier to construct; remanent fields, hysteresis, and eddy-currents, which are of concern in magnetic devices, are no longer relevant; and electrical fields required to control the orbit of the ions are not only much easier to create and control than the corresponding magnetic fields, they also set no upper mass limit on the ions that can be stored. These technical differences are a boon to new areas of fundamental experimental research, not only in atomic and molecular physics but also in the boundaries of these fields with chemistry and biology. For examples, studies of interactions with internally cold molecular ions will be particular useful for applications in astrophysics, while studies of solvated ionic clusters will be of relevance to aeronomy and biology.
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- Zijlstra, Jolande A, et al.
(författare)
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Different defibrillation strategies in survivors after out-of-hospital cardiac arrest.
- 2018
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Ingår i: Heart. - : BMJ. - 1355-6037 .- 1468-201X. ; 104:23, s. 1929-1936
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In the last decade, there has been a rapid increase in the dissemination of automated external defibrillators (AEDs) for prehospital defibrillation of out-of-hospital cardiac arrest patients. The aim of this study was to study the association between different defibrillation strategies on survival rates over time in Copenhagen, Stockholm, Western Sweden and Amsterdam, and the hypothesis was that non-EMS defibrillation increased over time and was associated with increased survival.METHODS: We performed a retrospective analysis of four prospectively collected cohorts of out-of-hospital cardiac arrest patients between 2008 and 2013. Emergency medical service (EMS)-witnessed arrests were excluded.RESULTS: A total of 22 453 out-of-hospital cardiac arrest patients with known survival status were identified, of whom 2957 (13%) survived at least 30 days postresuscitation. Of all survivors with a known defibrillation status, 2289 (81%) were defibrillated, 1349 (59%) were defibrillated by EMS, 454 (20%) were defibrillated by a first responder AED and 429 (19%) were defibrillated by an onsite AED and 57 (2%) were unknown. The percentage of survivors defibrillated by first responder AEDs (from 13% in 2008 to 26% in 2013, p<0.001 for trend) and onsite AEDs (from 14% in 2008 to 30% in 2013, p<0.001 for trend) increased. The increased use of these non-EMS AEDs was associated with the increase in survival rate of patients with a shockable initial rhythm.CONCLUSION: Survivors of out-of-hospital cardiac arrest are increasingly defibrillated by non-EMS AEDs. This increase is primarily due to a large increase in the use of onsite AEDs as well as an increase in first-responder defibrillation over time. Non-EMS defibrillation accounted for at least part of the increase in survival rate of patients with a shockable initial rhythm.
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