J/ψJ/\psi production and elliptic flow in relativistic heavy-ion collisions

Using a two-component model for charmonium production, which includes contributions from both the initial hard nucleon-nucleon scattering and from the regeneration in the quark-gluon plasma, we study the nuclear modification factor $R_{AA}$ and elliptic flow $v_2$ of $J/\psi$ in relativistic heavy ion collisions. For the expansion dynamics of produced hot dense matter, we introduce a schematic fireball model with its transverse acceleration determined from the pressure gradient inside the fireball and azimuthally anisotropic expansion parameterized to reproduce measured $v_2$ of light hadrons. We assume that light hadrons freeze out at the temperature of 120 MeV while charmonia at 160 MeV, similar to the kinetic and chemical freeze-out temperatures in the statistical model, respectively. For the properties of charmonia in the quark-gluon plasma, we use the screening mass between their charm and anticharm quarks and their dissociation cross sections given by the perturbative QCD (pQCD) in the leading order and up to the next-to-leading order, respectively. For the relaxation time of charm and anticharm quarks in the quark-gluon plasma, we also use the one calculated in the leading order of pQCD. Modeling the effect of higher-order corrections in pQCD by introducing multiplicative factors to the dissociation cross section of charmonia and the elastic scattering cross sections of charm and anticharm quarks, we find that this effect is small for the $R_{AA}$ of $J/\psi$ as they suppress the number of initially produced $J/\psi$ but enhance the number of regenerated ones. The higher-order corrections increase, however, the $v_2$ of $J/\psi$. Our results suggest that the $v_2$ of $J/\psi$ can play an important role in discriminating between $J/\psi$ production from the initial hard collisions and from the regeneration in the quark-gluon plasma.Comment: 15 pages, 14 figure

Forty-Four Pass Fibre Optic Loop for Improving the Sensitivity of Surface Plasmon Resonance Sensors

A forty-four pass fibre optic surface plasmon resonance sensor that enhances detection sensitivity according to the number of passes is demonstrated for the first time. The technique employs a fibre optic recirculation loop that passes the detection spot forty- four times, thus enhancing sensitivity by a factor of forty-four. Presently, the total number of passes is limited by the onset of lasing action of the recirculation loop. This technique offers a significant sensitivity improvement for various types of plasmon resonance sensors that may be used in chemical and biomolecule detections.Comment: Submitted for publication; patent disclosure submitte

Single quantum dot selection and tailor-made photonic device integration using nanoscale focus pinspot

Among the diverse platforms of quantum light sources, epitaxially grown semiconductor quantum dots (QDs) are one of the most attractive workhorses for realizing various quantum photonic technologies owing to their outstanding brightness and scalability. There exist various material systems for these QDs based on their appropriate emission bandwidth; however, only a few material systems have successfully grown single or low-density QDs, which are essential for quantum light sources. In most other material systems, it is difficult to realize low-density QDs, and the mesa-etching process is usually undergone in order to reduce their density. Nevertheless, the etching process irreversibly destroys the medium near the QD, which is detrimental to in-plane device integration. In this study, we apply a nondestructive luminescence picking method termed as nanoscale focus pinspot (NFP) using helium ion microscopy to reduce the luminous QD density while retaining the surrounding medium. Given that the NFP can precisely manipulate the luminescence at nanoscale resolution, a photonic device can be deterministically fabricated on the target QD matched from both spatial and spectral points of view. After applying the NFP, we extract only a single QD emission out of the high-density ensemble QD emission. Moreover, the photonic structure of a circular Bragg reflector is deterministically integrated with the selected QD, and the extraction efficiency of the QD emission has been improved 27 times. Furthermore, this technique does not destroy the medium and only controls the luminescence. Hence, it is highly applicable to various photonic structures, including photonic waveguides or photonic crystal cavities regardless of their materials.Comment: 16 pages, 5 figure

Low-Dose Recombinant Adeno-Associated Virus-Mediated Inhibition of Vascular Endothelial Growth Factor Can Treat Neovascular Pathologies Without Inducing Retinal Vasculitis

The wet form of age-related macular degeneration is characterized by neovascular pathologies that, if untreated, can result in edemas followed by rapid vision loss. Inhibition of vascular endothelial growth factor (VEGF) has been used to successfully treat neovascular pathologies of the eye. Nonetheless, some patients require frequent intravitreal injections of anti-VEGF drugs, increasing the burden and risk of complications from the procedure to affected individuals. Recombinant adeno-associated virus (rAAV)-mediated expression of anti-VEGF proteins is an attractive alternative to reduce risk and burden to patients. However, controversy remains as to the safety of prolonged VEGF inhibition in the eye. Here, we show that two out of four rAAV serotypes tested by intravitreal delivery to express the anti-VEGF drug conbercept lead to a dose-dependent vascular sheathing pathology that is characterized by immune cell infiltrates, reminiscent of vasculitis in humans. We show that this pathology is accompanied by increased expression in vascular cell adhesion molecule 1 (VCAM1) and intercellular adhesion molecule 1 (ICAM1), both of which promote extravasation of immune cells from the vasculature. While formation of the vascular sheathing pathology is prevented in immunodeficient Rag-1 mice that lack B and T cells, increased expression of VACM1 and ICAM1 still occurs, indicating that inhibition of VEGF function leads to expression changes in cell adhesion molecules that promote extravasation of immune cells. Importantly, a 10-fold lower dose of one of the vectors that cause a vascular sheathing pathology is still able to reduce edemas resulting from choroidal neovascularization without causing any vascular sheathing pathology and only a minimal increase in VCAM1 expression. The data suggest that treatments of neovascular eye pathologies with rAAV-mediated expression of anti VEGF drugs can be developed safely. However, viral load needs to be adjusted to the tropisms of the serotype and the expression pattern of the promoter

Percutaneous aspiration of lumbar zygapophyseal joint synovial cyst under fluoroscopic guidance -A case report-

A 51-year-old man with a 1-month history of lower back pain and radiating pain visited to our pain clinic. A magnetic resonance imaging (MRI) scan demonstrated a cyst like mass at the level of the L4-5 interspace and compression of the thecal sac and the nerve root on the right side. We performed percutaneous needle aspiration of the lumbar zygapophyseal joint synovial cyst under fluoroscopic guidance. The patient felt an immediate relief of symptoms after the aspiration, and had no signs or symptoms of recurrence at the follow-up 6 months later. No demonstrable lesion was found in the 6 months follow-up MRI

Prevalence of BRCA1 and BRCA2 Mutations in Korean Breast Cancer Patients

The incidence of breast cancer in Korea has been increasing in recent years, such that it is now the most common female cancer. Breast cancer in Korea is characterized by an earlier age of onset than in Western countries, suggesting that it would be related with genetic background. We assayed germline mutations in the BRCA genes to evaluate their genetic pathology in Korean breast cancer patients. The study subjects consisted of 173 patients at clinically higher risk and 109 unselected patients. Germline mutations in the entire coding sequences of the BRCA1 and BRCA2 genes were analyzed by Conformation-Sensitive Gel Electrophoresis (CSGE), and any aberrantly-sized band was sequenced. BRCA mutations were present in 12.7% of the high risk patients, compared with 2.8% of the unselected patients. Among high risk patients, mutations were most prevalent in patients with a family history of breast or first-degree ovarian cancer (22.1%), followed by those with male breast cancer (20%), bilateral breast cancer (20%), multiple organ cancer including breast (13%) and younger breast cancer patients (aged <35 yr) (8.1%). Moreover, BRCA mutations were detected in 34.8% of patients having two high-risk factors. These findings suggest that BRCA gene mutation analysis should be performed on Korean patients with high-risk factors for breast cancer