199 research outputs found
Cosmological contribution from population III stars in ultracompact minihalos
In this work, we investigate the effect of Population~III~(Pop.~III) stars in
ultracompact minihalos~(UCMHs) on the cosmic ionization history using the
Planck observation data. Although high-redshift astrophysics is not understood
yet, UCMHs could host the Pop.~III stars like the halos formed in the standard
structure formation scenario. Such Pop.~III stars would emit ionizing photons
during their main sequence and facilitate cosmic reionization in high
redshifts. To study their effects on the global ionization, we model the cosmic
reionization evolution based on the ``tanh"-type reionization model which is
expressed by with additional two parameters characterizing
the initial mass of UCMHs and the number density of UCMHs. We implement the
Monte Carlo Markov Chain analysis with the latest Planck observation data for
our reionization model. As the result, we found that if the UCMH initial mass
is larger than , the number density of UCMHs is
strictly limited. Then we obtained the constraint on the amplitude of the
primordial power spectrum through the constraint on the UCMH number density
like in the scales, , when we assume that the standard ``tanh"-type
reionization occurs by , so that we set .Comment: 12 pages, 7 figure
Translating nano-Hertz gravitational wave background into primordial perturbations taking account of the cosmological QCD phase transition
The evidence of the nano-Hertz stochastic gravitational wave (GW) background
is reported by multiple pulsar timing array collaborations. While a prominent
candidate of the origin is astrophysical from supermassive black hole binaries,
alternative models involving GWs induced by primordial curvature perturbations
can explain the inferred GW spectrum. Serendipitously, the nano-Hertz range
coincides with the Hubble scale during the cosmological quantum chromodynamics
(QCD) phase transition. The influence of the QCD phase transition can modify
the spectrum of induced GWs within the nano-Hertz frequency range,
necessitating careful analysis. We estimate GWs induced by power-law power
spectra of primordial curvature perturbations taking account of the QCD phase
transition. Then we translate the implication of the NANOGrav data into the
constraint on the power spectrum of the primordial curvature perturbation,
which suggests that one may miss the correct interpretation if neglecting the
QCD effect. We also derive fitting formulae for their amplitude and scale
dependence, helping to update the constraint in future experiments.Comment: 7 pages, 5 figure
Cbl-b regulates macrophage activation
Aging and overnutrition cause obesity in rodents and humans. It is well-known that obesity causes various diseases by producing insulin resistance (IR). Macrophages infiltrate the adipose tissue (AT) of obese individuals and cause chronic low-level inflammation associated with IR. Macrophage infiltration is regulated by the chemokines that are released from hypertrophied adipocytes and the immune cells in AT. Saturated fatty acids are recognized by toll-like receptor 4 (TLR4) and induce inflammatory responses in AT macrophages (ATMs). The inflammatory cytokines that are released from activated ATMs promote IR in peripheral organs, such as the liver, skeletal muscle and AT. Therefore, ATM activation is a therapeutic target for IR in obesity. The ubiquitin ligase Casitas b-lineage lymphoma-b (Cbl-b) appears to potently suppress macrophage migration and activation. Cbl-b is highly expressed in leukocytes and negatively regulates signals associated with migration and activation. Cbl-b deficiency enhances ATM accumulation and IR in aging- and diet-induced obese mice. Cbl-b inhibits migration-related signals and SFA-induced TLR4 signaling in ATMs. Thus, targeting Cbl-b may be a potential therapeutic strategy to reduce the IR induced by ATM activation. In this review, we summarize the regulatory functions of Cbl-b in ATMs
Primordial black holes and gravitational waves induced by exponential-tailed perturbations
Primordial black holes (PBHs) whose masses are in
have been extensively studied as a
candidate of whole dark matter (DM). One of the probes to test such a PBH-DM
scenario is scalar-induced stochastic gravitational waves (GWs) accompanied
with the enhanced primordial fluctuations to form the PBHs with frequency
peaked in the mHz band being targeted by the LISA mission. In order to utilize
the stochastic GWs for checking the PBH-DM scenario, it needs to exactly relate
the PBH abundance and the amplitude of the GWs spectrum. Recently in Kitajima
et al., the impact of the non-Gaussianity of the enhanced primordial curvature
perturbations on the PBH abundance has been investigated based on the peak
theory, and they found that a specific non-Gaussian feature called the
exponential tail significantly increases the PBH abundance compared with the
Gaussian case. In this work, we investigate the spectrum of the induced
stochastic GWs associated with PBH DM in the exponential-tail case. In order to
take into account the non-Gaussianity properly, we employ the diagrammatic
approach for the calculation of the spectrum. We find that the amplitude of the
stochastic GW spectrum is slightly lower than the one for the Gaussian case,
but it can still be detectable with the LISA sensitivity. We also find that the
non-Gaussian contribution can appear on the high-frequency side through their
complicated momentum configurations. Although this feature emerges under the
LISA sensitivity, it might be possible to obtain information about the
non-Gaussianity from GW observation with a deeper sensitivity such as the
DECIGO mission.Comment: 33 pages, 19 figure
The repeating dislodgement of an ASO device
Transcatheter closure with an Amplatzer Septal Occluder (ASO) has become the standard treatment for secundum atrial septal defect (ASD). However, this procedure is associated with complications, such as device dislodgement. A 52-year-old woman was admitted with exertional dyspnea. Transesophageal echocardiography showed an ASD involving a 29 mm defect. Calculated Qp/Qs was 5.6 and all the rims were > 5 mm, with the exception of the posterior rim, which was 3 mm. Transcatheter ASD closure with an ASO was performed under general anesthesia. During emergence from anesthesia, tachycardia developed and the ASO device became dislodged. Hemodynamic changes associated with the end of anesthetic administration were believed to have led to device dislodgement. In a second transcatheter ASD closure, a low dose of propofol and remifentanil was maintained during emergence from anesthesia to reduce hemodynamic changes. However, device dislodgement occurred with nonsustained ventricular tachycardia. Finally, surgical ASD closure was performed. The large defect size, high Qp/Qs, and rim deficiency may have predisposed to device dislodgement after transcatheter ASD closure with ASO. The risk of device dislodgement should be considered in advance of surgery and, in high-risk cases, the patient's cardiovascular status should be closely monitored
Uncoupling protein 3 attenuates generation of reactive oxygen species by interacting with thioredoxin 2 in the mitochondrial intermembrane space
Katsuya Hirasaka1*, Edward M Mills2, Shohei Kohno1, Tomoki Abe1, Chika Ikeda1, Tasuku Maeda1, Shigetada Kondo1, Ayako Maita1, Yuushi Okumura1 and Takeshi Nikawa1
Author Affiliations
1 Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima, 770-8503, Japan
2 Division of Pharmacology/Toxicology, University of Texas at Austin, Austin, TX 78712, USAPoster presentation
Uncoupling protein 3 (UCP3) is primarily expressed in the inner membrane of skeletal muscle mitochondria. It has been proposed that UCP3 reduces production of reactive oxygen species (ROS) and oxidative damage. However, the mechanisms by which UCP3 attenuates ROS production are not well understood. Here we report that UCP3 interacts with the non-processed form of thioredoxin 2 (Trx2), a redox protein that is localized in mitochondria, but not processed Trx2, which is involved in cellular responses to ROS. The hydrophilic sequences within the N-terminal tail of UCP3, which faces the intermembrane space, are necessary for binding to Trx2. In addition, Trx2 directly associated with UCP3 through a mitochondrial targeting signaling sequence, was processed in the intermembrane space, and thereby allowing redox reactions. A bimolecular fluorescence complementation analysis demonstrated that the interaction of these proteins occurs in the mitochondrial intermembrane space. Furthermore, increased UCP3 expression significantly attenuated ROS production in isolated mitochondrial without effects on membrane potential, however this effect is lost by Trx2 knock down. These results suggest that UCP3 binds to Trx2 in the mitochondrial intermembrane space and attenuates ROS production.Pharmac
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