Pentaquark searches at FOCUS

We find no evidence for high-energy photoproduction of pentaquarks at 1540 MeV/$c^2$, 1862 MeV/$c^2$, or 3099 MeV/$c^2$ using decay modes $pK_S^0$, $\Xi^-\pi^-$, and $D^{(*)-}p$, respectively.Comment: Proceedings from talk at 2004 DPF Meeting at University of California, Riversid

Intercalation of graphene on SiC(0001) via ion-implantation

Electronic devices based on graphene technology are catching on rapidly and the ability to engineer graphene properties at the nanoscale is becoming, more than ever, indispensable. Here, we present a new procedure of graphene functionalization on SiC(0001) that paves the way towards the fabrication of complex graphene electronic chips. The procedure resides on the well-known ion-implantation technique. The efficiency of the working principle is demonstrated by the intercalation of the epitaxial graphene layer on SiC(0001) with Bi atoms, which was not possible following standard procedures. Our results put forward the ion-beam lithography to nanostructure and functionalize desired graphene chips

Long-Distance Contributions to D^0-D^0bar Mixing Parameters

Long-distance contributions to the $D^0$-$\bar D^0$ mixing parameters $x$ and $y$ are evaluated using latest data on hadronic $D^0$ decays. In particular, we take on two-body $D \to PP$ and $VP$ decays to evaluate the contributions of two-body intermediate states because they account for $\sim 50$ of hadronic $D^0$ decays. Use of the diagrammatic approach has been made to estimate yet-observed decay modes. We find that $y$ is of order a few $\times 10^{-3}$ and $x$ of order $10^{-3}$ from hadronic $PP$ and $VP$ modes. These are in good agreement with the latest direct measurement of $D^0$-$\bar D^0$ mixing parameters using the $D^0 \to K_S \pi^+\pi^-$ and $K_S K^+ K^-$ decays by BaBar. We estimate the contribution to $y$ from the $VV$ modes using the factorization model and comment on the single-particle resonance effects and contributions from other two-body modes involving even-parity states.Comment: 18 pages and 1 figure; footnotes and references added; to appear in Phys. Rev.

The disarrayed mutation results in cell cycle and neurogenesis defects during retinal development in zebrafish

BACKGROUND: The vertebrate retina is derived from proliferative neuroepithelial cells of the optic cup. During retinal development, cell proliferation and the processes of cell cycle exit and neurogenesis are coordinated in neuroepithelial progenitor cells. Previous studies have demonstrated reciprocal influences between the cell cycle and neurogenesis. However the specific mechanisms and exact relationships of cell cycle regulation and neurogenesis in the vertebrate retina remain largely unknown. RESULTS: We have isolated and characterized a zebrafish mutant, disarrayed (dry(a64)), which exhibits retinal defects in cell cycle regulation and neurogenesis. By 42 hours post fertilization, disarrayed mutants show small eyes and a reduced forebrain. Other aspects of development appear normal. Although retinogenesis is delayed, mutant retinal cells eventually differentiate to all major cell types. Examination of the disarrayed mitotic cycle using BrdU and direct imaging techniques revealed that retinal neuroepithelial cells have an extended cell cycle period and reduced rate of cell cycle exit and neurogenesis, despite the fact that neurogenesis initiates at the appropriate time of development. Genetic mosaic analyses indicate that the cell cycle phenotype of disarrayed is cell-non-autonomous. CONCLUSION: The disarrayed mutant shows defects in both cell cycle regulation and neurogenesis and provides insights into the coordinated regulation of these processes during retinal development

Waiving Rights Goodbye: Class Action Waivers in Arbitration Agreements after Stolt-Nielsen v. AnimalFeeds International

This article first argues that to determine the enforceability of a class action waiver, courts should take a totality of the circumstances approach rather than adopting a bright-line rule. A set of defined factors that also allows courts to consider real-world issues facing litigants will provide a substantial framework for courts to interpret this area of the law and will lead to more consistent and well-reasoned outcomes in the future. These factors include: the probable size of each class member\u27s individual recovery, the potential for retaliation against class members, the awareness of potential class members that their rights have been violated, and other factors such as cost and convenience. Second, this article argues that the FAA should be amended to include a provision that directly addresses the issues that arise surrounding class action arbitration and class action waivers

The Two-Dimensional Square-Lattice S=1/2 Antiferromagnet Cu(pz)2_2(ClO4_4)2_2

We present an experimental study of the two-dimensional S=1/2 square-lattice antiferromagnet Cu(pz)$_2$(ClO$_4$)$_2$ (pz denotes pyrazine - $C_4H_4N_2$) using specific heat measurements, neutron diffraction and cold-neutron spectroscopy. The magnetic field dependence of the magnetic ordering temperature was determined from specific heat measurements for fields perpendicular and parallel to the square-lattice planes, showing identical field-temperature phase diagrams. This suggest that spin anisotropies in Cu(pz)$_2$(ClO$_4$)$_2$ are small. The ordered antiferromagnetic structure is a collinear arrangement with the magnetic moments along either the crystallographic b- or c-axis. The estimated ordered magnetic moment at zero field is m_0=0.47(5)mu_B and thus much smaller than the available single-ion magnetic moment. This is evidence for strong quantum fluctuations in the ordered magnetic phase of Cu(pz)$_2$(ClO$_4$)$_2$. Magnetic fields applied perpendicular to the square-lattice planes lead to an increase of the antiferromagnetically ordered moment to m_0=0.93(5)mu_B at mu_0H=13.5T - evidence that magnetic fields quench quantum fluctuations. Neutron spectroscopy reveals the presence of a gapped spin excitations at the antiferromagnetic zone center, and it can be explained with a slightly anisotropic nearest neighbor exchange coupling described by J_1^{xy}=1.563(13)meV and J_1^z=0.9979(2)J_1^{xy}

Pulsar Constraints on Neutron Star Structure and Equation of State

With the aim of constraining the structural properties of neutron stars and the equation of state of dense matter, we study sudden spin-ups, glitches, occurring in the Vela pulsar and in six other pulsars. We present evidence that glitches represent a self-regulating instability for which the star prepares over a waiting time. The angular momentum requirements of glitches in Vela indicate that at least 1.4% of the star's moment of inertia drives these events. If glitches originate in the liquid of the inner crust, Vela's `radiation radius' must exceed ~12 km for a mass of 1.4 solar masses. Observational tests of whether other neutron stars obey this constraint will be possible in the near future.Comment: 5 pages, including figures. To appear in Physical Review Letter

Correlation of Patient Symptoms With Labral and Articular Cartilage Damage in Femoroacetabular Impingement.

BackgroundFemoroacetabular impingement (FAI) can lead to labral and articular cartilage injuries as well as early osteoarthritis of the hip. Currently, the association of patient symptoms with the progression of labral and articular cartilage injuries due to FAI is poorly understood.PurposeTo evaluate the correlation between patient-reported outcome (PRO) scores and cartilage compositional changes seen on quantitative magnetic resonance imaging (MRI) as well as cartilage and labral damage seen during arthroscopic surgery in patients with FAI.Study designCohort study; Level of evidence, 3.MethodsPatients were prospectively enrolled before hip arthroscopic surgery for symptomatic FAI. Patients were included if they had cam-type FAI without radiographic arthritis. All patients completed PRO scores, including the Hip disability and Osteoarthritis Outcome Score (HOOS) and a visual analog scale for pain. MRI with mapping sequences (T1ρ and T2) on both the acetabular and femoral regions was performed before surgery to quantitatively assess the cartilage composition. During arthroscopic surgery, cartilage and labral injury grades were recorded using the Beck classification. Pearson and Spearman correlation coefficients were then obtained to evaluate the association between chondrolabral changes and PRO scores.ResultsA total of 46 patients (46 hips) were included for analysis (mean age, 35.5 years; mean body mass index [BMI], 23.9 kg/m2; 59% male). Increasing BMI was correlated with a more severe acetabular cartilage grade (ρ = 0.37; 95% CI, 0.08-0.65). A greater alpha angle was correlated with an increased labral tear grade (ρ = 0.59; 95% CI, 0.37-0.82) and acetabular cartilage injuries (ρ = 0.61; 95% CI, 0.42-0.80). With respect to PRO scores, increasing femoral cartilage damage in the anterosuperior femoral head region, as measured on quantitative MRI using T1ρ and T2 mapping, correlated with lower (worse) scores on the HOOS Activities of Daily Living (r = 0.35; 95% CI, 0.06-0.64), Symptoms (r = 0.32; 95% CI, 0.06-0.57), and Pain (r = 0.31; 95% CI, 0.06-0.55) subscales. There was no correlation between PRO scores and acetabular cartilage damage or labral tearing found on quantitative MRI or during arthroscopic surgery.ConclusionFemoral cartilage damage, as measured on T1ρ and T2 mapping, appears to have a greater correlation with clinical symptoms than acetabular cartilage damage or labral tears in patients with symptomatic FAI

Detection of grapevine fenleaf virus (GFLV) in infected grapevines by non-radioactive nucleic acid hybridisation

The nucleic acid hybridisation technique was adopted for the detection of grapevine fanleaf virus (GFLV) in grapevine tissues using a nonradioactive labeled cDNA. In crude plant sap a certain detection was not successful. Thus, a method was developed for the extraction of total RNA from a large number of samples in a microscale. By Northern blot hybridisation and by the more convenient slot blot technique GFLV infections could be detected. Comparing ELISA and slot blot hybridisation assay using identical plant material different results were obtained with some samples. This indicates different detection spectra for both techniques. The hybridisation assay has been found to be a suitable method by which a large number of samples from different grapevine tissues could be efficiently indexed for GFLV