| 1. |
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| 2. |
- Danielsson, Christian, et al.
(författare)
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Exploration of human, rat, and rabbit embryonic cardiomyocytes suggests K-channel block as a common teratogenic mechanism
- 2013
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Ingår i: Cardiovascular Research. - : Oxford University Press (OUP): Policy B. - 0008-6363 .- 1755-3245. ; 97:1, s. 23-32
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Tidskriftsartikel (refereegranskat)abstract
- Several drugs blocking the rapidly activating potassium (K-r) channel cause malformations (including cardiac defects) and embryonic death in animal teratology studies. In humans, these drugs have an established risk for acquired long-QT syndrome and arrhythmia. Recently, associations between cardiac defects and spontaneous abortions have been reported for drugs widely used in pregnancy (e.g. antidepressants), with long-QT syndrome risk. To investigate whether a common embryonic adverse-effect mechanism exists in the human, rat, and rabbit embryos, we made a comparative study of embryonic cardiomyocytes from all three species. less thanbrgreater than less thanbrgreater thanPatch-clamp and quantitative-mRNA measurements of K-r and slowly activating K (K-s) channels were performed on human, rat, and rabbit primary cardiomyocytes and cardiac samples from different embryo-foetal stages. The K-r channel was present when the heart started to beat in all species, but was, in contrast to human and rabbit, lost in rats in late organogenesis. The specific K-r-channel blocker E-4031 prolonged the action potential in a species- and development-dependent fashion, consistent with the observed K-r-channel expression pattern and reported sensitive periods of developmental toxicity. E-4031 also increased the QT interval and induced 2:1 atrio-ventricular block in multi-electrode array electrographic recordings of rat embryos. The K-s channel was expressed in human and rat throughout the embryo-foetal period but not in rabbit. less thanbrgreater than less thanbrgreater thanThis first comparison of mRNA expression, potassium currents, and action-potential characteristics, with and without a specific K-r-channel blocker in human, rat, and rabbit embryos provides evidence of K-r-channel inhibition as a common mechanism for embryonic malformations and death.
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| 3. |
- Danielsson, Gudmundur, et al.
(författare)
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Percutaneous transluminal angioplasty of crural arteries: diabetes and other factors influencing outcome
- 2001
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Ingår i: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1532-2165 .- 1078-5884. ; 21:5, s. 432-436
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: to evaluate the efficacy of percutaneous transluminal angioplasty (PTA) of the crural arteries. PATIENTS AND METHODS: a retrospective review of patients treated with PTA of at least one crural artery during an 8-year period (1990--1997). RESULTS: one hundred and fifty-five legs in 140 consecutive patients (mean age 74 years, range 38--91 years) were treated. In 76% a more proximal lesion was also treated. After 1 year, results were significantly better in non-diabetics (improvement rate of 66% vs 32%p <0.05). The outcome for patients with a combination of diabetes, heart disease and renal disease was significantly worse compared to all other patients with an improvement rate of only 9% after 1 year. Patients alive and not amputated at 1 year were significantly more common (p <0.05) among non-diabetics (90%), compared to diabetics (66%). The 1-year mortality for the whole group was 15%, significantly higher for diabetic patients (p =0.04). CONCLUSION: PTA of crural arteries produces reasonably good results in non-diabetic patients. Diabetic patients were doing worse than non-diabetics after a year, though 1-month results were not significantly different. Patients with diabetes, heart disease and renal disease make a high-risk group that has a significantly worse outcome.
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| 4. |
- Aad, G., et al.
(författare)
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Commissioning of the ATLAS Muon Spectrometer with cosmic rays
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 875-916
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the calibration method of the detector response and of the alignment system, the track reconstruction efficiency and the momentum measurement. The results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy proton-proton collisions.
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| 5. |
- Aad, G., et al.
(författare)
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Studies of the performance of the ATLAS detector using cosmic-ray muons
- 2011
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 71:3
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Tidskriftsartikel (refereegranskat)abstract
- Muons from cosmic-ray interactions in the atmosphere provide a high-statistics source of particles that can be used to study the performance and calibration of the ATLAS detector. Cosmic-ray muons can penetrate to the cavern and deposit energy in all detector subsystems. Such events have played an important role in the commissioning of the detector since the start of the installation phase in 2005 and were particularly important for understanding the detector performance in the time prior to the arrival of the first LHC beams. Global cosmic-ray runs were undertaken in both 2008 and 2009 and these data have been used through to the early phases of collision data-taking as a tool for calibration, alignment and detector monitoring. These large datasets have also been used for detector performance studies, including investigations that rely on the combined performance of different subsystems. This paper presents the results of performance studies related to combined tracking, lepton identification and the reconstruction of jets and missing transverse energy. Results are compared to expectations based on a cosmic-ray event generator and a full simulation of the detector response.
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| 6. |
- Aad, G., et al.
(författare)
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The ATLAS Inner Detector commissioning and calibration
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 787-821
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1 +/- 0.9 mu m and a relative momentum resolution sigma (p) /p=(4.83 +/- 0.16)x10(-4) GeV(-1)xp (T) have been measured for high momentum tracks.
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| 7. |
- Aad, G., et al.
(författare)
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The ATLAS Simulation Infrastructure
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 823-874
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Tidskriftsartikel (refereegranskat)abstract
- The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.
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| 8. |
- Abat, E., et al.
(författare)
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The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:2
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Tidskriftsartikel (refereegranskat)abstract
- A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability.
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| 9. |
- Abat, E., et al.
(författare)
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The ATLAS TRT barrel detector
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS TRT barrel is a tracking drift chamber using 52,544 individual tubular drift tubes. It is one part of the ATLAS Inner Detector, which consists of three sub-systems: the pixel detector spanning the radius range 4 to 20 cm, the semiconductor tracker (SCT) from 30 to 52 cm, and the transition radiation tracker ( TRT) from 56 to 108 cm. The TRT barrel covers the central pseudo-rapidity region |eta| < 1, while the TRT endcaps cover the forward and backward eta regions. These TRT systems provide a combination of continuous tracking with many measurements in individual drift tubes ( or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. This paper describes the recently-completed construction of the TRT Barrel detector, including the quality control procedures used in the fabrication of the detector.
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| 10. |
- Abat, E., et al.
(författare)
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The ATLAS TRT electronics
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:6
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system.
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| 11. |
- Abat, E., et al.
(författare)
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The ATLAS TRT end-cap detectors
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The ATLAS TRT end-cap is a tracking drift chamber using 245,760 individual tubular drift tubes. It is a part of the TRT tracker which consist of the barrel and two end-caps. The TRT end-caps cover the forward and backward pseudo-rapidity region 1.0 < vertical bar eta vertical bar < 2.0, while the TRT barrel central eta region vertical bar eta vertical bar < 1.0. The TRT system provides a combination of continuous tracking with many measurements in individual drift tubes ( or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. Along with other two sub-systems, namely the Pixel detector and Semi Conductor Tracker (SCT), the TRT constitutes the ATLAS Inner Detector. This paper describes the recently completed and installed TRT end-cap detectors, their design, assembly, integration and the acceptance tests applied during the construction.
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| 12. |
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| 13. |
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| 14. |
- Aronsson, Patrik, 1983, et al.
(författare)
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Soluble guanylate cyclase mediates the relaxation of healthy and inflamed bladder smooth muscle by aqueous nitric oxide.
- 2023
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Ingår i: Frontiers in physiology. - 1664-042X. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Due to its chemical properties, functional responses to nitric oxide (NO) are often difficult to examine. In the present study, we established a method to produce NO in an aqueous solution and validated its capacity to evoke functional responses in isolated rat bladders. Furthermore, we compared the NO responses to the commonly used NO donor sodium nitroprusside (SNP). We also investigated the impact of ongoing inflammation on the involvement of soluble guanylate cyclase (sGC) dependent signaling in NO relaxation. Methods: A setup to produce an aqueous NO solution was established, allowing the production of an aqueous solution containing a calculated NO concentration of 2mM. Sixty male Sprague-Dawley rats received either no treatment (controls) or cyclophosphamide (CYP; 100mg*kg-1 i.p., 60h prior to the experiment) to induce experimental cystitis. Bladder strip preparations were mounted in organ baths and studied at basal tension or pre-contracted with methacholine (3μM). Aqueous NO solution (40-400μL; 2mM corresponding to 4-40μM) or SNP (1-1,000μM) was added cumulatively in increasing concentrations. Relaxation to aqueous NO was also studied in the presence of the sGC inhibitor ODQ (0.25-25μM). The expression of sGC was investigated by immunohistochemical analysis. Results: The NO solution caused functional relaxations in both controls and inflamed bladder preparations. NO-induced relaxations were significantly greater in inflamed bladder strips at basal tension, whereas no differences were seen in methacholine pre-contracted strips. In the presence of the sGC inhibitor ODQ in a high concentration, the NO-evoked relaxations were abolished in both control and inflamed preparations. At a lower concentration of ODQ, only NO relaxations in inflamed preparations were attenuated. Immunohistochemical analysis showed that sGC was expressed in the detrusor and mucosa, with a significantly lower expression in the inflamed detrusor. Conclusion: In the present study, we found that aqueous NO solution induces relaxation of the rat detrusor by activating soluble guanylate cyclase in both control and inflamed bladder strips. Induction of inflammation conceivably leads to decreased sGC expression in the detrusor, which may explain the different susceptibility towards inhibition of sGC in inflamed versus control tissue. The use of an aqueous NO solution should be further considered as a valuable complement to the pharmacological tools currently used.
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| 15. |
- Ashoorioon, Amjad, et al.
(författare)
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1/N resolution to inflationary eta-problem
- 2012
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 713:4-5, s. 353-357
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Tidskriftsartikel (refereegranskat)abstract
- We observe that the dominant one loop contribution to the graviton propagator in the theory of N (N >> 1) light scalar fields phi(a) (with masses smaller than M-pI/root N) minimally coupled to Einstein gravity is proportional to N while that of graviton-scalar-scalar interaction vertex is N independent. We use this to argue that the coefficient of the R phi(2)(a) term appearing at one loop level is 1/N suppressed. This observation provides a resolution to the quantum eta-problem, that the slow-roll parameter eta receives order one quantum loop corrections for inflationary models built within the framework of scalar fields minimally coupled to Einstein gravity, for models involving large number of fields. As particular examples, we employ this to argue in favor of the absence of eta-problem in multi-field inflationary scenarios of M-flation and N-flation.
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| 16. |
- Ashoorioon, Amjad, et al.
(författare)
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Effects of nonlinear dispersion relations on non-Gaussianities
- 2011
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :6, s. 034-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the effect of non-linear dispersion relations on the bispectrum. In particular, we study the case were the modified relations do not violate the WKB condition at early times, focusing on a particular example which is exactly solvable: the Jacobson-Corley dispersion relation with quartic correction with positive coefficient to the squared linear relation. We find that the corrections to the standard result for the bispectrum are suppressed by a factor H-2/p(c)(2) where p(c) is the scale where the modification to the dispersion relation becomes relevant. The modification is mildly configuration-dependent and equilateral configurations are more suppressed with respect to the local ones, by a factor of one percent. There is no configuration leading to enhancements. We then analyze the results in the framework of particle creation using the approximate gluing method of Brandenberger and Martin, which relates more directly to the modeling of the trans-Planckian physics via modifications of the vacuum at a certain cutoff scale. We show that the gluing method overestimates the leading order correction to the spectrum and bispectrum by one and two orders, respectively, in We discuss the various approximation and conclude that for dispersion relations not violating WKB at early times the particle creation is small and does not lead to enhanced contributions to the bispectrum. We also show that in many cases enhancements do not our when modeling the trans-Planckian physics via modifications of the vacuum at a certain cutoff scale. Most notably they are only of order O(1) when the Bogolyubov coefficients accounting for particle creation are determined by the Wronskian condition and the minimization of the uncertainty between the field and its conjugate momentum.
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| 17. |
- Banerjee, Souvik, et al.
(författare)
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Bubble needs strings
- 2021
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :3
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we want to emphasize the pivotal role played by strings in the model realizing de Sitter using an expanding bubble, proposed and subsequently developed in [1-3]. Contrary to the Randall-Sundrum model of brane-localized gravity, we use the end points of radially stretched strings to obtain matter sourcing gravity induced on the bubble wall. This allows us to reinterpret the possible volume divergence coming from naive dimensional reduction as mass renormalization in four dimensional particle physics. Furthermore, we argue that the residual time dependence in the bulk, pointed out by some recent work as a possible shortcoming of such models, is automatically cured in presence of these stringy sources.
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| 18. |
- Banerjee, Souvik, et al.
(författare)
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Curing with Hemlock : Escaping the swampland using instabilities from string theory
- 2021
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Ingår i: International Journal of Modern Physics D. - : World Scientific. - 0218-2718. ; 30:14
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Tidskriftsartikel (refereegranskat)abstract
- In this essay, we will take a wonderful ride on a dark bubble with strings attached, which carries our universe out of the swampland and makes it realizable in the landscape of string theory. To find the way to the landscape, we make use of apparently hostile corners of the swampland and their instabilities.
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| 19. |
- Banerjee, Souvik, et al.
(författare)
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Dark bubbles : decorating the wall
- 2020
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Ingår i: Journal of High Energy Physics (JHEP). - : SPRINGER. - 1126-6708 .- 1029-8479. ; :4
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the difficulty of constructing de Sitter vacua in string theory, a new approach was proposed in arXiv:1807.01570 and arXiv:1907.04268, where four dimensional de Sitter space was realized as the effective cosmology, with matter and radiation, on an expanding spherical bubble that mediates the decay of non supersymmetric AdS(5) to a more stable AdS5 in string theory. In this third installment, we further expand on this scenario by considering the backreaction of matter in the bulk and on the brane in terms of how the brane bends. We compute the back reacted metric on the bent brane as well as in the five dimensional bulk. To further illuminate the effect of brane-bending, we compare our results with an explicit computation of the five dimensional graviton propagator using a holographic prescription. Finally we comment on a possible localization of four dimensional gravity in our model using two colliding branes.
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| 20. |
- Banerjee, Souvik, et al.
(författare)
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Dark bubbles and black holes
- 2021
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :9
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we study shells of matter and black holes on the expanding bubbles realizing de Sitter space, that were proposed in [4]. We construct explicit solutions for a rigid shell of matter as well as black hole like solutions. The latter of these can also be used to construct Randall-Sundrum braneworld black holes in four dimensions.
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| 21. |
- Banerjee, Souvik, et al.
(författare)
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De Sitter cosmology on an expanding bubble
- 2019
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :10
-
Tidskriftsartikel (refereegranskat)abstract
- Constructing an explicit compactification yielding a metastable de Sitter (dS) vacuum in a UV consistent string theory is an incredibly difficult open problem. Motivated by this issue, as well as the conjecture that all non-supersymmetric AdS vacua must decay, we discuss the alternative possibility of realizing an effective four-dimensional dS cosmology on a codimension-one bubble wall separating two AdS(5) vacua. The construction further elaborates on the scenario of , where the aforementioned cosmology arises due to a non-perturbative decay and is embedded in a five-dimensional bulk in a time- dependent way. In this paper we discuss the relation between this scenario and the weak gravity conjecture and further develop the details of the four-dimensional cosmology. We provide a bulk interpretation for the dS temperature as the Unruh temperature experienced by an accelerated observer riding the bubble. A source of four-dimensional matter arises from a string cloud in the bulk, and we examine the consequences for the particle mass spectrum. Furthermore, we show how effective four-dimensional Einstein gravity on the bubble is obtained from the five-dimensional Gauss equation. We conclude by outlining some implications that this paradigm will have for holography, inflation, the standard model, and black holes.
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| 22. |
- Banerjee, Souvik, et al.
(författare)
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Emergent de Sitter cosmology from decaying Anti-de Sitter Space
- 2018
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 121:26
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Tidskriftsartikel (refereegranskat)abstract
- Recent developments in string compactifications demonstrate obstructions to the simplest constructions of low energy cosmologies with positive vacuum energy. The existence of obstacles to creating scale-separated de Sitter solutions indicates a UV/IR puzzle for embedding cosmological vacua in a unitary theory of quantum gravity. Motivated by this puzzle, we propose an embedding of positive energy Friedmann-Lemaitre-Robertson-Walker cosmology within string theory. Our proposal involves confining 4D gravity on a brane which mediates the decay from a nonsupersymmetric five-dimensional anti-de Sitter false vacuum to a true vacuum. In this way, it is natural for a 4D observer to experience an effective positive cosmological constant coupled to matter and radiation, avoiding the need for scale separation or a fundamental de Sitter vacuum.
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| 23. |
- Banerjee, Souvik, et al.
(författare)
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Features of a dark energy model in string theory
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:12
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Tidskriftsartikel (refereegranskat)abstract
- In this article we clear up misconceptions concerning the dark bubble model as a realization of dark energy in string theory. In particular we point out important differences with Randall-Sundrum, and explain why gravity neither is, nor need be, localized on the dark bubble.
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| 24. |
- Banerjee, Souvik, et al.
(författare)
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The dark bubbleography
- 2024
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :2
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Tidskriftsartikel (refereegranskat)abstract
- We present the holographic construction of the dark bubble model of dark energy and highlight the pivotal role played by the non-normalizable modes. Following the route of holographic renormalization, we show that the non-normalizable modes are essential for having a vanishing mass for the induced graviton in any braneworld model. We then apply this idea in the computation of the propagator on the wall of the dark bubble introduced in [1].
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| 25. |
- Barausse, Enrico, et al.
(författare)
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Prospects for fundamental physics with LISA
- 2020
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Ingår i: General Relativity and Gravitation. - : SPRINGER/PLENUM PUBLISHERS. - 0001-7701 .- 1572-9532. ; 52:8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, which is of programmatic rather than quantitative nature, we aim to further delineate and sharpen the future potential of the LISA mission in the area of fundamental physics. Given the very broad range of topics that might be relevant to LISA,we present here a sample of what we view as particularly promising fundamental physics directions. We organize these directions through a "science-first" approach that allows us to classify how LISA data can inform theoretical physics in a variety of areas. For each of these theoretical physics classes, we identify the sources that are currently expected to provide the principal contribution to our knowledge, and the areas that need further development. The classification presented here should not be thought of as cast in stone, but rather as a fluid framework that is amenable to change with the flow of new insights in theoretical physics.
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| 26. |
- Basile, Ivano, et al.
(författare)
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Shedding light on dark bubble cosmology
- 2024
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Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; :2
-
Tidskriftsartikel (refereegranskat)abstract
- Dark bubble cosmology is an alternative paradigm to compactification, which can circumvent issues of moduli stabilization and scale separation. In this paper we investigate how electromagnetic fields can be incorporated in this framework. Worldvolume fields backreact on the ambient universe in which the bubble expands, which in turn affects the energy-momentum distribution and the effective gravity induced on the brane. We compute these effects, showing that the resulting four-dimensional cosmology consistently includes electromagnetic waves.
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| 27. |
- Bena, I., et al.
(författare)
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Antibranes cannot become black
- 2013
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 87:10, s. 104023-
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Tidskriftsartikel (refereegranskat)abstract
- When D-branes are inserted in flux backgrounds of opposite charge, the resulting solution has a certain singularity in the fluxes. Recently it has been argued, using numerical solutions, that for anti-D3 branes in the Klebanov-Strassler background, these singularities cannot be cloaked by a horizon, which strongly suggests they are not physical. In this paper we provide an analytic proof that the singularity of all codimension-three antibrane solutions (such as anti-D6 branes in massive type IIA supergravity or anti-D3 branes smeared on the T-3 of R-3 x T-3 with fluxes) cannot be hidden behind a horizon and that the charge of black branes with smooth event horizons must have the same sign as the charge of the flux background. Our result indicates that infinitesimally blackening the antibranes immediately triggers brane-flux annihilation and strengthens the intuition that antibranes placed in flux with positive charge immediately annihilate against it.
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| 28. |
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| 29. |
- Blaback, Johan, et al.
(författare)
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Constructing stable de Sitter in M-theory from higher curvature corrections
- 2019
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Ingår i: Journal of High Energy Physics (JHEP). - : SPRINGER. - 1126-6708 .- 1029-8479. ; :9
-
Tidskriftsartikel (refereegranskat)abstract
- We consider dimensional reductions of M-theory on T-7/Z(2)(3) with the inclusion of arbitrary metric flux and spacetime filling KK monopoles. With these ingredients at hand, we are able to construct a novel family of non-supersymmetric yet tachyon free Minkowski extrema. These solutions are supported by pure geometry with no extra need for gauge fluxes and possess a fully stable perturbative mass spectrum, up to a single flat direction. Such a direction corresponds to the overall internal volume, with respect to which the scalar potential exhibits a no-scale behavior. We then provide a mechanism that lifts the flat direction to give it a positive squared mass while turning Mkw(4) into dS(4). The construction makes use of the combined effect of G(7) flux and higher curvature corrections. Our solution is scale separated and the quantum corrections are small. Finally we speculate on novel possibilities when it comes to scale hierarchies within a given construction of this type, and possible issues with the choice of quantum vacuum.
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| 30. |
- Blaback, Johan, et al.
(författare)
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Lifshitz backgrounds from 10d supergravity
- 2010
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :2, s. 095-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate whether 4-dimensional static and cosmological Lifshitz solutions can be found from deforming the existing (A)dS(4) compactifications in IIA and IIA. supergravity. Using a well motivated compactification Ansatz on SU(3)-structure manifolds with 19 undetermined parameters we demonstrate that this is not the case in ordinary IIA supergravity, thereby generalising previous nogo results in different ways. On the other hand, for IIA* we construct explicit cosmological Lifshitz solutions. We also consider solutions with non-constant scalars and are able to find simple static and cosmological Lifshitz solutions in IIB* supergravity and a Euclidean Lifshitz solution in ordinary Euclidean IIB supergravity, which is similar to a non-extremal deformation of the D-instanton. The latter solutions have z = -2.
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| 31. |
- Blabaeck, J., et al.
(författare)
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Universal dS vacua in STU-models
- 2015
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :10
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Tidskriftsartikel (refereegranskat)abstract
- Stable de Sitter solutions in minimal F-term supergravity are known to lie close to Minkowski critical points. We consider a class of STU-models arising from type IIB compactifications with generalised fluxes. There, we apply an analytical method for solving the equations of motion for the moduli fields based on the idea of treating derivatives of the superpotential of different orders up to third as independent objects. In particular, supersymmetric and no-scale Minkowski solutions are singled out by physical reasons. Focusing on the study of dS vacua close to supersymmetric Minkowski points, we are able to elaborate a complete analytical treatment of the mass matrix based on the sGoldstino bound. This leads to a class of interesting universal dS vacua. We finally explore a similar possibility around no-scale Minkowski points and discuss some examples.
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| 32. |
- Blom, Helena, 1970-, et al.
(författare)
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Multiple violence victimisation associated with sexual ill health and sexual risk behaviours in Swedish youth
- 2016
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Ingår i: European journal of contraception & reproductive health care. - : Informa UK Limited. - 1362-5187 .- 1473-0782. ; 21:1, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To address the associations between emotional, physical and sexual violence, specifically multiple violence victimisation, and sexual ill health and sexual risk behaviours in youth, as well as possible gender differences.Methods: A cross-sectional population-based survey among sexually experienced youth using a questionnaire with validated questions on emotional, physical, and sexual violence victimisation, sociodemographics, health risk behaviours, and sexual ill health and sexual risk behaviours. Proportions, unadjusted/adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.Results: The participants comprised 1192 female and 1021 male students aged 15 to 22 years. The females had experienced multiple violence (victimisation with two or three types of violence) more often than the males (21% vs. 16%). The associations between multiple violence victimisation and sexual ill health and sexual risk behaviours were consistent for both genders. Experience of/involvement in pregnancy yielded adjusted ORs of 2.4 (95% CI 1.5-3.7) for females and 2.1 (95% CI 1.3-3.4) for males, and early age at first intercourse 2.2 (95% CI 1.6-3.1) for females and 1.9 (95% CI 1.2-3.0) for males. No significantly raised adjusted ORs were found for non-use of contraceptives in young men or young women, or for chlamydia infection in young men.Conclusions: Several types of sexual ill health and sexual risk behaviours are strongly associated with multiple violence victimisation in both genders. This should be taken into consideration when counselling young people and addressing their sexual and reproductive health.
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| 33. |
- Blom, Helena, et al.
(författare)
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Strong association between earlier abuse and revictimization in youth
- 2014
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Ingår i: BMC Public Health. - : Springer Science and Business Media LLC. - 1471-2458. ; 14:14
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Tidskriftsartikel (refereegranskat)abstract
- Background: Violence victimization among youth is recognized as a public health problem. The objective was to analyze the risk pattern of emotional, physical, and sexual abuse during the past 12 months by gender, sociodemographic factors, health risk behaviors, and exposure to abuse before the age of 15, among young men and women attending youth health centers in Sweden.Methods: A cross-sectional survey was conducted using a nationally representative sample of youth health centers. A total of 2,250 young women and 920 young men aged 15-23 completed a self-administered questionnaire. Odds ratios (OR) and adjusted odds ratios (AOR) with 95% CI were calculated.Results: A consistent and strong association was noted between exposure to all types of violence during the past year and victimization before the age of 15 for all types of violence for both women and men. The only exceptions were childhood sexual victimization and sexual violence during the past year for men. Younger age was associated with all violence exposure for the women and with emotional violence for the men. For the women, drug use was associated with all types of violence, while the association with hazardous alcohol use and not living with parents was restricted to physical and sexual violence exposure, present smoking was restricted to emotional and physical violence exposure, and partnership and living in urban areas were restricted to sexual violence. For men, not being partnered, hazardous alcohol consumption, and drug use meant increased risk for physical violence, while smoking and living in urban areas were associated with sexual violence. After adjustment, immigration had no association with violence exposure.Conclusions: Violence victimization in young men and women is often not a single experience. Findings underline the importance of early interventions among previously abused youth.
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| 34. |
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| 35. |
- Blom, Helena, 1970-
(författare)
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Violence exposure among Swedish youth
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundViolence is a global public health problem and violence among youth is a matter of high priority. Adolescence and young adulthood are important periods for the foundation of future health. Youth victimization may have serious health consequences, making it important to address the occurrence and socio-medical context for possible interventions against violence.AimsTo analyze prevalence, risk patterns and gender differences in emotional, physical, sexual, and multiple-violence victimizations and the associations between violence victimization and sexual ill health, sexual risk behaviors and mental health in Swedish youth.MethodsA cross sectional study using two samples, a national sample from nine youth health centers in Sweden and a population-based sample from a middle-sized Swedish city. The questionnaire included standardized instruments addressing violence exposure (NorAQ), socio-demographics, mental and sexual ill-health and sexual risk behaviors, alcohol and substance use. Proportions and crude and adjusted odds ratios with a 95% CI were calculated.ResultsA total of 2,250 young women and 920 men, aged 15-23, answered the questionnaire at the youth health centers. In upper secondary school, 1,658 women and 1,589 men, aged 15-22, answered the questionnaire.High prevalence rates with gendered differences both in rates and in co-occurrence of different types of violence were found. Women were more often exposed to emotional violence and sexual violence than men, while men were more often physically victimized. For both women and men, violence victimization before the age of 15 was strongly associated with all types of violence victimizations during the past year.Strong associations were found between multiple-violence victimization and poor mental health in both genders. Among the sexually experienced students, consistent associations between lifetime multiple-violence victimization and various sexual ill-health and sexual risk behaviors were found in both genders, except for non-contraceptive use.ConclusionsHigh prevalence of violence victimization in youth and strong associations between victimization, especially multiple victimization, and poor mental and sexual health were found. This needs to be recognized and addressed in social and medical settings.
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| 36. |
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| 37. |
- Blåbäck, Johan, et al.
(författare)
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A new light on the darkest corner of the landscape
- 2018
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- otivated by the recently proposed bounds on the slow-roll parameters forscalar potentials arising from string/M-theory compactifications, a.k.a. theRefined de Sitter Swampland conjecture, we explore the sharpness of suchconstraints within 4D supergravities coming from compactifications of massivetype IIA string theory onT6/(Z2×Z2). With the aid of a numerical technique,known as differential evolution, we are able to find a de Sitter extremum whichis fully metastable up to one single flat direction. This solution is supported byspacetime filling sources such as O6 planes and KK monopoles. Our exampleviolates the bound imposed by this conjecture
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| 38. |
- Blåbäck, Johan, et al.
(författare)
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Accelerated Universes from type IIA Compactifications
- 2014
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :003
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We study slow-roll accelerating cosmologies arising from geometric compactifications of type IIA string theory on T^6/(Z_2 x Z_2). With the aid of a genetic algorithm, we are able to find quasi-de Sitter backgrounds with both slow-roll parameters of order 0.1
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| 39. |
- Blåbäck, Johan, et al.
(författare)
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(Anti-)brane backreaction beyond perturbation theory
- 2012
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 2012:2, s. 025-
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Tidskriftsartikel (refereegranskat)abstract
- We improve on the understanding of the backreaction of anti-D6-branes in a flux background that is mutually BPS with D6-branes. This setup is analogous to the study of the backreaction of anti-D3-branes inserted in the KS throat, but does not require us to smear the anti-branes or do a perturbative analysis around the BPS background. We solve the full equations of motion near the anti-D6-branes and show that only two boundary conditions are consistent with the equations of motion. Upon invoking a topological argument we eliminate the boundary condition with regular H flux since it cannot lead to a solution that approaches the right kind of flux away from the anti-D6-branes. This leaves us with a boundary condition which has singular, but integrable, H flux energy density.
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| 40. |
- Blåbäck, Johan, et al.
(författare)
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Fully stable dS vacua from generalised fluxes
- 2013
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 8, s. 054-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the possible existence of (meta-)stable de Sitter vacua within \cN=1 compactifications with generalised fluxes. With the aid of an algorithm inspired by the method of differential evolution, we were able to find three novel examples of completely tachyon-free de Sitter extrema in a non-isotropic type IIB model with non-geometric fluxes. We also analyse the surroundings of the aforementioned points in parameter space and chart the corresponding stability regions. These happen to occur at small values of the cosmological constant compared to the AdS scale.
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| 41. |
- Blåbäck, Johan, et al.
(författare)
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Localised anti-branes in non-compact throats at zero and finite T
- 2015
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :2
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the 3-form singularities that are typical to anti-brane solutions in supergravity and check whether they can be cloaked by a finite temperature horizon. For anti-D3-branes in the Klebanov-Strassler background, this was already shown numerically to be impossible when the branes are partially smeared. In this paper, we present analytic arguments that also localised branes remain with singular 3-form fluxes at both zero and finite temperature. These results may have important, possibly fatal, consequences for constructions of meta-stable de Sitter vacua through uplifting.
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| 42. |
- Blåbäck, Johan, et al.
(författare)
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Resolving anti-brane singularities through time-dependence
- 2013
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :2, s. 61-
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Tidskriftsartikel (refereegranskat)abstract
- In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.In this note we discuss a possible resolution of the flux singularities associated with the insertion of branes in backgrounds supported by fluxes that carry charges opposite to the branes. We present qualitative arguments that such a setup could be unstable both in the closed and open string sector. The singularities in the fluxes then get naturally resolved by taking the true solution to be a time-dependent process in which flux gets attracted towards the brane and subsequently annihilates.
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| 43. |
- Blåbäck, Johan, 1985-
(författare)
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Singular Fluxes in Ten and Eleven Dimensions : Sources, Singularities, Fluxes and Spam
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The energy content of our present universe is dominated by the dark-energy, or vacuum energy, which provides accelerated cosmic expansion. Dark energy has a possible effective explanation through a positive cosmological constant. The problem present in any fundamental theory is to explain the underlying dynamics of what gives rise to the cosmological constant.In string theory there are several scenarios that could give insight into what is behind the positive cosmological constant. One such construction uses anti-branes to achieve a net positive energy density of the vacuum. Anti-branes refers in this case to branes placed in a background with oppositely charged flux. As backreaction and localisation procedures are considered for anti-brane constructions a certain kind of singularity arise. This new type of singularity is present in the surrounding flux, which is not directly sourced by the brane.This thesis, and the works contained, considers several aspects of this type of singularity. The first such flux singularity were discovered for the anti-D3-branes, in which the approximations and assumptions of partial smearing and perturbative expansions are used. Included in this thesis are new anti-D6-brane solutions which are placed in oppositely charged flux. It is shown that after the anti-D6-branes are localised, they display the same type of singularity. The strength of this result lies in that it is possible to show the presence of the singularity beyond partial smearing and perturbative expansions. Similar to the anti-D6-brane solutions, new anti-M2-brane solutions are presented. These solutions are also argued to display the same type of singularity.The investigation into the presence of the singularity is just the first step. The second step is to deduce whether this singularity is acceptable and can somehow be resolved. Included in this thesis are two works that considers exactly this. One way of interpreting the singularity is through the absence of a no-force condition between the brane and the surrounding flux. This interpretation leads to the conclusion that the singularity is present due to the use of static Ansätze in a system that is inherently time dependent. Through an adiabatic approach it is here argued that this interpretation leads to a new type of instability.Another way of arguing for a possible resolution of this singularity is whether or not the singularity can be cloaked by an event horizon. This condition have been successful in other systems with singularities. It is argued in this thesis that it is not possible to hide the flux singularity behind a horizon. This leads to one out of two conclusions, either the condition is not a necessary one and the singularity can be resolved in a static manner, or the singularity does not have a resolution.To put these works in context the current singularities from anti-branes program is briefly reviewed to give a full overview of the current situation of these investigations.
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| 44. |
- Blåbäck, Johan, et al.
(författare)
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Smeared versus localised sources in flux compactifications
- 2010
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :12, s. 043-
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Tidskriftsartikel (refereegranskat)abstract
- We investigate whether vacuum solutions in flux compactifications that are obtained with smeared sources (orientifolds or D-branes) still survive when the sources are localised. This seems to rely on whether the solutions are BPS or not. First we consider two sets of BPS solutions that both relate to the GKP solution through T-dualities: (p + 1)-dimensional solutions from spacetime-filling Op-planes with a conformally Ricci-flat internal space, and p-dimensional solutions with Op-planes that wrap a 1-cycle inside an everywhere negatively curved twisted torus. The relation between the solution with smeared orientifolds and the localised version is worked out in detail. We then demonstrate that a class of non-BPS AdS(4) solutions that exist for IASD fluxes and with smeared D3-branes (or analogously for ISD fluxes with anti-D3-branes) does not survive the localisation of the (anti) D3-branes. This casts doubts on the stringy consistency of non-BPS solutions that are obtained in the limit of smeared sources.
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| 45. |
- Blåbäck, Johan, et al.
(författare)
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The problematic backreaction of SUSY-breaking branes
- 2011
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :8, s. 105-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we investigate the localisation of SUSY-breaking branes which, in the smeared approximation, support specific non-BPS vacua. We show, for a wide class of boundary conditions, that there is no flux vacuum when the branes are described by a genuine delta-function. Even more, we find that the smeared solution is the unique solution with a regular brane profile. Our setup consists of a non-BPS AdS(7) solution in massive IIA supergravity with smeared anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.
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| 46. |
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| 47. |
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| 48. |
- Brynjolfsson, E. J., et al.
(författare)
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Black hole thermodynamics and heavy fermion metals
- 2010
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Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :8, s. 027-
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Tidskriftsartikel (refereegranskat)abstract
- Heavy fermion alloys at critical doping typically exhibit non-Fermi-liquid behavior at low temperatures, including a logarithmic or power law rise in the ratio of specific heat to temperature as the temperature is lowered. Anomalous specific heat of this type is also observed in a simple class of gravitational dual models that exhibit anisotropic scaling with dynamical critical exponent z > 1.
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| 49. |
- Brynjolfsson, E. J., et al.
(författare)
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Holographic superconductors with Lifshitz scaling
- 2010
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Ingår i: Journal of physics. A, Mathematical and theoretical. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 43:6, s. 065401-
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Tidskriftsartikel (refereegranskat)abstract
- Black holes in asymptotically Lifshitz spacetime provide a window onto finite temperature effects in strongly coupled Lifshitz models. We add a Maxwell gauge field and charged matter to a recently proposed gravity dual of (2+ 1)-dimensional Lifshitz theory. This gives rise to charged black holes with scalar hair, which correspond to the superconducting phase of holographic superconductors with z > 1 Lifshitz scaling. Along the way we analyze the global geometry of static, asymptotically Lifshitz black holes at the arbitrary critical exponent z > 1. In all known exact solutions there is a null curvature singularity in the black hole region, and, by a general argument, the same applies to generic Lifshitz black holes.
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| 50. |
- Carlson, Karin, et al.
(författare)
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Language policy for a bilingual faculty
- 2005
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Ingår i: Bi- and multilingual universities, Helsinki, Finland, Sept 1-3, 2005.
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Konferensbidrag (refereegranskat)abstract
- The Faculty of Science and Technology of Uppsala University is for all practical purposes a bilingual institution, using both Swedish and English in education and research. Extensive use of English in teaching, and also in intrauniversity communication, permits recruitment of nonSwedishspeaking students, researchers and professors, and also prepares our students forinternational careers. However, the introduction of English has been somewhat haphazard, not taking into account possible negative effects on communication in Swedish, nor on students'learning.In order to improve students' and professors' language skills, and achieve a good balance between Swedish and English, the faculty board appointed a language committee in 2003 whose task was to propose a language policy for the faculty. A first part, stating as a main goal that all communication from and within the faculty should have the highest quality possible, has been adopted by the board. A second part including language planning with respect to status, corpus, and acquisition for both Swedish and English to accomplish this goal was sent to the board of the faculty in May, 2005. Implementation of this policy will affect all faculty activities, especially education. Suggestedannual reports on language status will raise our present minimal knowledge about possible domain losses and allow for relevant countermeasures.
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