155 research outputs found

    Towards Axion Monodromy Inflation with Warped KK-Modes

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    We present a particularly simple model of axion monodromy: Our axion is the lowest-lying KK-mode of the RR-2-form-potential C2C_2 in the standard Klebanov-Strassler throat. One can think of this inflaton candidate as being defined by the integral of C2C_2 over the S2S^2 cycle of the throat. It obtains an exponentially small mass from the IR-region in which the S2S^2 shrinks to zero size both with respect to the Planck scale and the mass scale of local modes of the throat. Crucially, the S2S^2 cycle has to be shared between two throats, such that the second locus where the S2S^2 shrinks is also in a warped region. Well-known problems like the potentially dangerous back-reaction of brane/antibrane pairs and explicit supersymmetry breaking are not present in our scenario. However, the inflaton back-reaction starts to deform the geometry strongly once the field excursion approaches the Planck scale. We derive the system of differential equations required to treat this effect quantitatively. Numerical work is required to decide whether back-reaction makes the model suitable for realistic inflation. While we have to leave this crucial issue to future studies, we find it interesting that such a simple and explicit stringy monodromy model allows an originally sub-Planckian axion to go through many periods with full quantitative control before back-reaction becomes strong. Also, the mere existence of our ultra-light throat mode (with double exponentially suppressed mass) is noteworthy.Comment: 28 pages, 3 figures; v2: references added; v3: Corrected an underestimate of supergravity back-reaction in Eq. (36); results changed accordingly; added section 6 which develops the methodology for the 10d non-linear back-reaction; added reference

    Non-Markovian quantum state diffusion for absorption spectra of molecular aggregates

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    In many molecular systems one encounters the situation where electronic excitations couple to a quasi-continuum of phonon modes. That continuum may be highly structured e.g. due to some weakly damped high frequency modes. To handle such a situation, an approach combining the non-Markovian quantum state diffusion (NMQSD) description of open quantum systems with an efficient but abstract approximation was recently applied to calculate energy transfer and absorption spectra of molecular aggregates [Roden, Eisfeld, Wolff, Strunz, PRL 103 (2009) 058301]. To explore the validity of the used approximation for such complicated systems, in the present work we compare the calculated (approximative) absorption spectra with exact results. These are obtained from the method of pseudomodes, which we show to be capable of determining the exact spectra for small aggregates and a few pseudomodes. It turns out that in the cases considered, the results of the two approaches mostly agree quite well. The advantages and disadvantages of the two approaches are discussed

    Pathophysiology of ageing, longevity and age related diseases

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    On April 18, 2007 an international meeting on Pathophysiology of Ageing, Longevity and Age-Related Diseases was held in Palermo, Italy. Several interesting topics on Cancer, Immunosenescence, Age-related inflammatory diseases and longevity were discussed. In this report we summarize the most important issues. However, ageing must be considered an unavoidable end point of the life history of each individual, nevertheless the increasing knowledge on ageing mechanisms, allows envisaging many different strategies to cope with, and delay it. So, a better understanding of pathophysiology of ageing and age-related disease is essential for giving everybody a reasonable chance for living a long and enjoyable final part of the life

    Combined optical coherence tomography morphologic and fractional flow reserve hemodynamic assessment of non- culprit lesions to better predict adverse event outcomes in diabetes mellitus patients: COMBINE (OCT–FFR) prospective study. Rationale and design

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    Contains fulltext : 172158.pdf (publisher's version ) (Open Access)BACKGROUND: Fractional flow reserve (FFR) is a widely used tool for the identification of ischaemia-generating stenoses and to guide decisions on coronary revascularisation. However, the safety of FFR-based decisions in high-risk subsets, such as patients with Diabetes Mellitus (DM) or vulnerable stenoses presenting thin-cap fibro-atheroma (TCFA), is unknown. This study will examine the impact of optical coherence tomography (OCT) plaque morphological assessment and the identification of TCFA, in combination with FFR to better predict clinical outcomes in DM patients. METHODS: COMBINE (OCT-FFR) is a prospective, multi-centre study investigating the natural history of DM patients with >/=1 angiographically intermediate target lesion in three subgroups of patients; patients with FFR negative lesions without TCFA (group A) and patients with FFR negative lesions with TCFA (group B) as detected by OCT and to compare these two groups with each other, as well as to a third group with FFR-positive, PCI-treated intermediate lesions (group C). The study hypothesis is that DM patients with TCFA (group B) have a worse outcome than those without TCFA (group A) and also when compared to those patients with lesions FFR </=0.80 who underwent complete revascularisation. The primary endpoint is the incidence of target lesion major adverse cardiac events (MACE); a composite of cardiac death, myocardial infarction or rehospitalisation for unstable/progressive angina in group B vs. group A. CONCLUSION: COMBINE (OCT-FFR) is the first prospective study to examine whether the addition of OCT plaque morphological evaluation to FFR haemodynamic assessment of intermediate lesions in DM patients will better predict MACE and possibly lead to new revascularisation strategies. Trial Registration Netherlands Trial Register: NTR5376

    Genomic analysis of circulating tumor DNA using a melanoma-specific UltraSEEK Oncogene Panel

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    The analysis of circulating tumor DNA provides a minimally invasive molecular interrogation that has the potential to guide treatment selection and disease monitoring. Here, the authors evaluated a custom UltraSEEK melanoma panel for the MassARRAY system, probing for 61 mutations over 13 genes. The analytical sensitivity and clinical accuracy of the UltraSEEK melanoma panel was compared with droplet digital PCR. The blinded analysis of 68 mutations detected in 48 plasma samples from stage IV melanoma patients revealed a concordance of 88% between the two platforms. Further comparison of both methods for the detection of BRAF V600E mutations in 77 plasma samples demonstrated a Cohen\u27s κ of 0.826 (bias-corrected and accelerated 95% CI, 0.669-0.946). These results indicate that the UltraSEEK melanoma panel is as sensitive as droplet digital PCR for the detection of circulating tumor DNA in this cohort of patients but highlight the need for detected variants to be confirmed orthogonally to mitigate any false-positive results. The MassARRAY system enables rapid and sensitive genotyping for the detection of multiple melanoma-associated mutations in plasma

    Rapid Changes in Synaptic Strength After Mild Traumatic Brain Injury

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    Traumatic brain injury (TBI) affects millions of Americans annually, but effective treatments remain inadequate due to our poor understanding of how injury impacts neural function. Data are particularly limited for mild, closed-skull TBI, which forms the majority of human cases, and for acute injury phases, when trauma effects and compensatory responses appear highly dynamic. Here we use a mouse model of mild TBI to characterize injury-induced synaptic dysfunction, and examine its progression over the hours to days after trauma. Mild injury consistently caused both locomotor deficits and localized neuroinflammation in piriform and entorhinal cortices, along with reduced olfactory discrimination ability. Using whole-cell recordings to characterize synaptic input onto piriform pyramidal neurons, we found moderate effects on excitatory or inhibitory synaptic function at 48 h after TBI and robust increase in excitatory inputs in slices prepared 1 h after injury. Excitatory increases predominated over inhibitory effects, suggesting that loss of excitatory-inhibitory balance is a common feature of both mild and severe TBI. Our data indicate that mild injury drives rapidly evolving alterations in neural function in the hours following injury, highlighting the need to better characterize the interplay between the primary trauma responses and compensatory effects during this early time period
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