The Thermal Abundance of Semi-Relativistic Relics

Approximate analytical solutions of the Boltzmann equation for particles that are either extremely relativistic or non-relativistic when they decouple from the thermal bath are well established. However, no analytical formula for the relic density of particles that are semi-relativistic at decoupling is yet known. We propose a new ansatz for the thermal average of the annihilation cross sections for such particles, and find a semi-analytical treatment for calculating their relic densities. As examples, we consider Majorana- and Dirac-type neutrinos. We show that such semi-relativistic relics cannot be good cold Dark Matter candidates. However, late decays of meta-stable semi-relativistic relics might have released a large amount of entropy, thereby diluting the density of other, unwanted relics.Comment: 22 pages, 5 figures. Comments and references adde

Spin and chirality orderings of the one-dimensional Heisenberg spin glass with the long-range power-law interaction

The ordering of the one-dimensional Heisenberg spin glass interacting via the long-range power-law interaction is studied by Monte Carlo simulations. Particular attention is paid to the possible occurrence of the ``spin-chirality decoupling'' for appropriate values of the power-law exponent \sigma. Our result suggests that, for intermediate values of $\sigma$, the chiral-glass order occurs at finite temperatures while the standard spin-glass order occurs only at zero temperature.Comment: Proceedings of the Highly Frustrated Magnetism (HFM2006) conference. To appear in a special issue of J. Phys. Condens. Matte

X-Ray Fluctuations from Locally Unstable Advection-Dominated Disks

The response of advection-dominated accretion disks to local disturbances is examined by one-dimensional numerical simulations. It is generally believed that advection-dominated disks are thermally stable. We, however, find that any disurbance added onto accretion flow at large radii does not decay so rapidly that it can move inward with roughly the free-fall velocity. Although disturbances continue to be present, the global disk structure will not be modified largely. This can account for persistent hard X-ray emission with substantial variations observed in active galactic nuclei and stellar black hole candidates during the hard state. Moreover, when the disturbance reaches the innermost parts, an acoustic wave emerges, propagating outward as a shock wave. The resultant light variation is roughly (time) symmetric and is quite reminiscent of the observed X-ray shots of Cygnus X-1.Comment: plain TeX, 11 pages, without figures; to be published in ApJ Lette

Exponential lower bound on the highest fidelity achievable by quantum error-correcting codes

On a class of memoryless quantum channels which includes the depolarizing channel, the highest fidelity of quantum error-correcting codes of length n and rate R is proven to be lower bounded by 1-exp[-nE(R)+o(n)] for some function E(R). The E(R) is positive below some threshold R', which implies R' is a lower bound on the quantum capacity.Comment: Ver.4. In vers.1--3, I claimed Theorem 1 for general quantum channels. Now I claim this only for a slight generalization of depolarizing channel in this paper because Lemma 2 in vers.1--3 was wrong; the original general statement is proved in quant-ph/0112103. Ver.5. Text sectionalized. Appeared in PRA. The PRA article is typographically slightly crude: The LaTeX symbol star, used as superscripts, was capriciously replaced by the asterisk in several places after my proof readin

Transitive X-ray spectrum and PeV gamma-ray cutoff in the M87 jet: Electron "Pevatron"

We propose a modified version of the X-ray spectral index and an intrinsic cutoff frequency of inverse Compton radiation from the brightest knot of the M87 jet, in conjunction with an application of the new conceptions of injection and diffusive shock acceleration (DSA) of electrons in magnetized filamentary plasma to the specified source. The drop of the X-ray flux density in a transitive frequency region is associated with the interplay of ordinary synchrotron cooling and weaker magnetic fields concomitant with the smaller scale filaments that allow the electron injection, while the radio-optical synchrotron continuum is dominantly established by the major electrons that are quasi-secularly bound to larger filaments. With reference to, particularly, the updated external Compton model, we demonstrate that in the Klein-Nishina regime fading inverse Comptonization, the injected electrons can be stochastically energized up to a Lorentz factor as high as $5\times 10^{10}$ in the temporal competition with diffuse synchrotron cooling; this value is larger than that attainable for a simple DSA scenario based on the resonant scattering diffusion of the gyrating electrons bound to a supposed magnetic field homogeneously pervading the entire knot. The upper limits of the photon frequency boosted via conceivable inverse Compton processes are predicted to be of the common order of $\sim 10^{30}$ Hz. The variability of the broadband spectrum is also discussed in comparison to the features of a blazar light curve. The present scenario of a peta-eV (PeV; $10^{15}$ eV) electron accelerator, the "Pevatron," might provide some guidance for exploring untrod hard X-ray and gamma-ray bands in forthcoming observations.Comment: 34 pages, 6 figures, matches version published in Ap

Mycorrhizal Fungi Increased Early Growth of Tropical Tree Seedlings in Adverse Soil

The rate of reforestation has increased throughout the countries in Southeast Asia region during the last 20 years. At the same time, inconvenient situations such as forest destruction, forest exploitation, illegal logging, clear-cut forest areas, old agricultural lands, post-wildfire areas, conversion of natural forests into plantations, resettlement areas, mine lands, and amended adverse soils have also been increasing significantly. Mycorrhizas, hovewer, play important role to increase plant growth, enrich nutrient content and enhance survival rates of forest tree species in temperate and sub-tropical regions. Unfortunately, a little information so far is available regarding the effect of mycorrhizas on growth of tree species growing in tropical forests. In relevant, several experiments were carried out to determine whether ectomycorrhizal (ECM) fungi and arbuscular mycorrhizal (AM) fungi can enhance mycorrhizal colonization, nutrient content, and plant growth of some tropical rain forest tree species in Indonesia under nursery and field conditions. The families of tropical tree species used in the experiment were Thymelaeaceae (Aquilaria crassna), Leguminosae (Sesbania grandifolia), Guttiferae (Ploiarium alternifolium and Calophyllum hosei), Apocynaceae (Dyera polyphylla and Alstonia scholaris), and Dipterocarpaceae (Shorea belangeran). These families are important as they provide timber and non-timber forest products (NTFPs). This paper discusses the role of mycorrhizal fungi in increasing early growth of tropical tree seedlings in adverse soil

A Pooled Analysis of Multicenter Cohort Studies of 123I-mIBG Imaging of Sympathetic Innervation for Assessment of Long-Term Prognosis in Heart Failure

ObjectivesThe study objectives were to create a cardiac metaiodobenzylguanidine (mIBG) database using multiple prospective cohort studies and to determine the quantitative iodine-123–labeled mIBG indices for identifying patients with chronic heart failure (HF) at greatest and lowest risk of lethal events.BackgroundAlthough the prognostic value of cardiac mIBG imaging in patients with HF has been shown, clinical use of this procedure has been limited. It is required to define universally accepted quantitative thresholds for high and low risk that could be used as an aid to therapeutic decision-making using a large cohort database.MethodsSix prospective HF cohort studies were updated, and the individual datasets were combined for the present patient-level analysis. The database consisted of 1,322 patients with HF followed up for a mean interval of 78 months. Heart-to-mediastinum ratio (HMR) and washout rate of cardiac mIBG activity were the primary cardiac innervation markers. The primary outcome analyzed was all-cause death.ResultsLethal events were observed in 326 patients, and the population mortality rate was 5.6%, 11.3%, and 19.7% at 1, 2, and 5 years, respectively. Multivariate Cox proportional hazard model analysis for all-cause mortality identified age (p < 0.0001), New York Heart Association (NYHA) functional class (p < 0.0001), late HMR of cardiac mIBG activity (p < 0.0001), and left ventricular ejection fraction (LVEF) (p = 0.0029) as significant independent predictors. Analysis of the 512-patient subpopulation with B-type natriuretic peptide (BNP) results showed BNP (p < 0.0001), greater NYHA functional class (p = 0.0002), and late HMR (p = 0.0011) as significant predictors, but LVEF was not. The receiver-operating characteristic–determined threshold of HMR (1.68) identified patients at significantly increased risk in any LVEF category. Survival rates decreased progressively with decreasing HMR, with 5-year all-cause mortality rates >7% annually for HMR <1.25, and <2% annually for HMR ≥1.95. Addition of HMR to clinical information resulted in a significant net reclassification improvement of 0.175 (p < 0.0001).ConclusionsPooled analyses of independent cohort studies confirmed the long-term prognostic value of cardiac mIBG uptake in patients with HF independently of other markers, such as NYHA functional class, BNP, and LVEF, and demonstrated that categoric assessments could be used to define meaningful thresholds for lethal event risk

AIRE Functions As an E3 Ubiquitin Ligase

Autoimmune regulator (AIRE) gene mutation is responsible for the development of autoimmune-polyendocrinopathy-candidiasis ectodermal dystrophy, an organ-specific autoimmune disease with monogenic autosomal recessive inheritance. AIRE is predominantly expressed in medullary epithelial cells of the thymus and is considered to play important roles in the establishment of self-tolerance. AIRE contains two plant homeodomain (PHD) domains, and the novel role of PHD as an E3 ubiquitin (Ub) ligase has just emerged. Here we show that the first PHD (PHD1) of AIRE mediates E3 ligase activity. The significance of this finding was underscored by the fact that disease-causing missense mutations in the PHD1 (C311Y and P326Q) abolished its E3 ligase activity. These results add a novel enzymatic function for AIRE and suggest an indispensable role of the Ub proteasome pathway in the establishment of self-tolerance, in which AIRE is involved

Post-transplant lymphoproliferative disorder involving the ovary as an initial manifestation: a case report

<p>Abstract</p> <p>Introduction</p> <p>Because the normal ovary is assumed to be devoid of lymphoid tissue, it is unusual for it to be an initial manifestation of malignant lymphoma. This case is the first report, to our knowledge, of post-transplant lymphoproliferative disorder involving the ovary as an initial manifestation.</p> <p>Case presentation</p> <p>Twenty-nine weeks after a living renal transplantation, a 38-year-old Japanese female, whose ethnic origin was Asian, presented with abdominal pain and a chronic high fever. Computed tomography revealed a right ovarian tumor and liver metastases. The patient underwent oophrectomy based on the clinical diagnosis of liver metastasis from the primary ovarian tumor. The pathological diagnosis was Epstein-Barr Virus-associated post-transplant lymphoproliferative disorder. While ovarian malignant lymphoma has a poor prognosis, complete remission of liver involvement in this case was achieved only with a reduction of immunosuppressants.</p> <p>Conclusion</p> <p>Clinicians should remember that malignant lymphoma could initially involve the ovary, especially if the patient is immunosuppressed after transplantation therapy.</p