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Department of PhysicsMajor mergers between two sub-clusters drive shocks with Mach number, Ms ??? 2-4 inside the hot ???intracluster medium???(ICM) with temperature, T ??? 10^7 ???10^8 K and plasma beta, ?? ??? 50???100. Those merger-driven shocks, like most astrophysical shocks, are collisionless shocks and Cosmic-ray (CR) are expected to be accelerated at such shocks through Diffusive Shock Acceleration (DSAa.k.a 1st-order Fermi acceleration). Mpc-scale diffuse radio synchrotron emissions from the outskirts of galaxy clusters (i.e., the so-called radio relics) indicate electron acceleration at ICM shocks and future observation of ??0-decay gamma-ray emission could provide an evidence for the production of CR protons as well. To investigate the kinetic plasma processes that govern the particle preacceleration for DSA at ICM shocks, we performed Particle-in-Cell (PIC) simulations with relevant parameters for ICM plasmas. In particular, both electron and proton are energized effectively through the preacceleration mechanism mediated by the multi-scale plasma waves in the shocks with Ms ??? 2.3, and so the origin of observed radio relics could be explained through such preacceleration process. In addition, considering the results obtained from our PIC simulations, we proposed a DSA model for CR proton acceleration and examined the feasibility of detecting gamma-ray from galaxy clusters. We have confirmed that the predicted gamma-ray emission is below the Fermi-LAT upper limits for observed clusters. Our findings will help to understand high-energy astrophysical processes in galaxy clusters.ope

Cosmic Ray Acceleration and Nonthermal Radiation at Accretion Shocks in the Outer Regions of Galaxy Clusters

Cosmology models predict that external accretion shocks form in the outer region of galaxy clusters due to supersonic gas infall from filaments and voids in the cosmic web. They are characterized by high sonic and Alfv\'enic Mach numbers, $M_s\sim10-10^2$ and $M_A\sim10^2-10^3$, and propagate into weakly magnetized plasmas of $\beta\equiv P_g/P_B\gtrsim10^2$. Although strong accretion shocks are expected to be efficient accelerators of cosmic rays (CRs), nonthermal signatures of shock-accelerated CRs around clusters have not been confirmed, and detailed acceleration physics at such shocks has yet to be understood. In this study, we first establish through two-dimensional particle-in-cell simulations that at strong high-$\beta$ shocks electrons can be pre-energized via stochastic Fermi acceleration owing to the ion-Weibel instability in the shock transition region, possibly followed by injection into diffusive shock acceleration. Hence, we propose that the models derived from conventional thermal leakage injection may be employed for the acceleration of electrons and ions at accretion shocks as well. Applying these analytic models to numerical shock zones identified in structure formation simulations, we estimate nonthermal radiation, such as synchrotron and inverse-Compton (IC) emission due to CR electrons, and $\pi^0$-decay $\gamma$-rays due to CR protons, around simulated clusters. Our models with the injection parameter, $Q\approx3.5-3.8$, predict synthetic synchrotron maps, which seem consistent with recent radio observations of the Coma cluster. However, the detection of nonthermal IC X-rays and $\gamma$-rays from accretion shocks would be quite challenging. We suggest that the proposed analytic models may be adopted as generic recipes for CR production at cosmological shocks.Comment: 21 pages, 12 figure

Radiofrequency Ablation of Thyroid Nodules: Basic Principles and Clinical Application

Radiofrequency (RF) ablation has been gaining popularity as a minimally invasive treatment for benign thyroid nodules regardless of the extent of the solid component. RF ablation of benign nodules demonstrated volume reductions of 33–58% after one month and 51–85% after six months, while solving nodule-related clinical problems. RF ablation has recently shown positive short-term results for locoregional control as well as symptom improvement in patients with recurrent thyroid cancers. This paper reviews the basic physics, indications, patient preparation, devices, procedures, clinical results, and complications of RF ablation

Microinstabilities in the Transition Region of Weak Quasi-perpendicular Intracluster Shocks

Microinstabilities play important roles in both entropy generation and particle acceleration in collisionless shocks. Recent studies have suggested that in the transition region of quasi-perpendicular (Q(perpendicular to)) shocks in the high-beta (beta = P-gas/P-B) intracluster medium (ICM), the ion temperature anisotropy due to the reflected-gyrating ions could trigger the Alfven ion cyclotron (AIC) instability and the ion-mirror instability, while the electron temperature anisotropy induced by magnetic field compression could excite the whistler instability and the electron-mirror instability. Adopting the numerical estimates for ion and electron temperature anisotropies found in the particle-in-cell (PIC) simulations of Q(perpendicular to) shocks with sonic Mach numbers, M-s = 2-3, we carry out a linear stability analysis for these microinstabilities. The kinetic properties of the microinstabilities and the ensuing plasma waves on both ion and electron scales are described for wide ranges of parameters, including beta and the ion-to-electron mass ratio. In addition, the nonlinear evolution of the induced plasma waves are examined by performing 2D PIC simulations with periodic boundary conditions. We find that for beta approximate to 20-100, the AIC instability could induce ion-scale waves and generate shock surface ripples in supercritical shocks above the AIC critical Mach number, M-AIC* approximate to 2.3. Also, electron-scale waves are generated primarily by the whistler instability in these high-beta shocks. The resulting multiscale waves from electron to ion scales are thought to be essential in the electron injection to diffusive shock acceleration in Q(perpendicular to) shocks in the ICM

Pengaruh pemberian reward terhadap peningkatan motivasi belajar pendidikan agama Islam kelas X-2 SMA Mujahidin Perak Surabaya

Alat pembelajaran merupakan suatu teknik untuk mencapai tujuan. Dengan adanya berbagai teknik pembelajaran diharapkan kegiatan belajar mengajar dapat berjalan sesuai dengan tujuan pendidikan, namun dalam kenyataannya masih ada siswa yang tidak fokus pada pelajaran, untuk itu diperlukan dorongan yang sesuai dan dapat meningkatkan motivasi belajar siswa. Adapun salah satu cara yang digunakan untuk mendorong agar para siswa lebih termotivasi untuk mencapai tujuan pembelajaran adalah dengan diterapkannya reward, dengan menerapkan reward diharapkan dapat meningkatkan motivasi belajar siswa, karena dengan adanya reward akan menciptakan suasana belajar yang menyenangkan dalam proses belajar mengajar. Pemberian reward ini dapat menimbulkan motivasi sehingga siswa akan antusias dalam belajar materi Pendidikan Agama Islam. Dalam kegiatan belajar mengajar memang perlu siswa itu diberi reward sebagai salah satu pengehargaan bagi mereka yang berprestasi dalam proses pembelajaran. Tujuan penelitian ini adalah untuk mengetahui bagaimana penerapan reward pada mata pelajaran Pendidikan Agama Islam, bagaimana motivasi belajar siswa pada mata pelajaran Pendidikan Agama Islam, serta adakah pengaruh reward terhadap peningkatan motivasi belajar Pendidikan Agama Islam siswa kelas X-2 SMA Mujahidin Perak Surabaya. Untuk mengetahui pengaruh pemberian reward terhadap peningkatan motivasi belajar Pendidikan Agama Islam di SMA Mujahidin Perak Surabaya, penulis menggunakan metode regresi linear sederhana yang dibantu dengan program spss, serta dengan menggunakan metode dokumentasi, angket,interview dan observasi. Adapun metode analisis yang digunakan adalah analisis data dengan melaksanakan uji validitas, uji reliabilitas dan uji t dengan taraf signifikansi 5%. Hasil penelitian dari analisis data yang diperoleh dari hasil penelitian mengenai pengaruh reward terhadap peningkatan motivasi belajar Pendidikan Agama Islam mempunyai pengaruh yang signifikan untuk meningkatkan motivasi belajar Pendidikan Agama Islam yaitu sebesar 60,2%

Heterogeneous nuclear ribonucleoprotein (hnRNP) L promotes DNA damage-induced cell apoptosis by enhancing the translation of p53

The tumor suppressor p53 is an essential gene in the induction of cell cycle arrest, DNA repair, and apoptosis. p53 protein is induced under cellular stress, blocking cell cycle progression and inducing DNA repair. Under DNA damage conditions, it has been reported that post-transcriptional regulation of p53 mRNA contributes to the increase in p53 protein level. Here we demonstrate that heterogeneous nuclear ribonucleoprotein (hnRNP) L enhances p53 mRNA translation. We found that hnRNP L is increased and binds to the 5' UTR of p53 mRNA in response to DNA damage. Increased hnRNP L caused enhancement of p53 mRNA translation. Conversely, p53 protein levels were decreased following hnRNP L knock-down, rendering them resistant to apoptosis and arrest in the G2/M phase after DNA damage. Thus, our findings suggest that hnRNP L functions as a positive regulator of p53 translation and promotes cell cycle arrest and apoptosis.11Ysciescopu