Preliminary site report for the 2005 ICDP-USGS deep corehole in the Chesapeake Bay impact crater

First report for the ICDP-USGS 1.7-km-deep corehole drilled into the central part of the Chesapeake Bay impact crater during 2005

ϕ\phi photoproduction on the proton at EγE_{\gamma} = 1.5 - 2.9 GeV

Differential cross sections at $t=t_{\text{min}}$ and decay asymmetries for the $\gamma p\rightarrow\phi p$ reaction have been measured using linearly polarized photons in the range 1.5 to 2.9 GeV. These cross sections were used to determine the Pomeron strength factor. The cross sections and decay asymmetries are consistently described by the $t$-channel Pomeron and pseudoscalar exchange model in the $E_{\gamma}$ region above 2.37 GeV. In the lower energy region, an excess over the model prediction is observed in the energy dependence of the differential cross sections at $t=t_{\text{min}}$. This observation suggests that additional processes or interference effects between Pomeron exchange and other processes appear near the threshold region.Comment: 6 pages, 7 figure

Epigenetic regulation in neonatal ECFCs following intrauterine exposure to gestational diabetes

poster abstractGestational diabetes (GDM) complicates up to 10% of pregnancies. In addition to acute risks, the children of diabetic mothers have an increased risk of obesity, diabetes, and hypertension, starting in childhood. While the causes of this increased risk are unknown, previous studies in our lab have identified functional deficits in endothelial colony forming cells (ECFCs) isolated from the cord blood of GDM pregnancies. This study focused on identifying genes that have altered epigenetic modifications that result in abnormal mRNA and protein expression in ECFCs from the cord blood GDM pregnancies. The objective of this study was to identify mRNA expression and DNA methylation alterations in ECFCs that may help identify the causes of ECFC dysfunction following intrauterine exposure to GDM. ECFCs were obtained from control and GDM pregnancies. DNA, RNA, and protein samples were isolated in parallel from ECFCs. RNA microarray analysis using the Affymetrix Human 1.0 Gene Array was used to identify gene expression alterations in GDM ECFCs compared to control ECFCs. Genome-wide DNA methylation was assessed using an Infinium 450K Methylation Array for DNA samples at >450,000 CpG sites. Correlation analysis was performed to identify possible sites that have altered CpG methylation and RNA expression. RNA expression results were validated using qRT-PCR and western blotting. Bisulfite sequencing of genomic DNA from the ECFCs was performed to identify additional sites with altered methylation for regions not included in the DNA methylation array. Of the 28,000 genetic loci tested, 596 mRNAs were altered between control and GDM ECFCs (p<0.01). More stringent criteria identified 38 genes for further investigation by limiting analysis to genes that exhibited increased or decreased expression by at least 50%, with a p<0.01. PLAC8 was identified as being increased 5-fold by microarray analysis, a result which was confirmed in two cohorts by qRT-PCR and western blotting. Analysis of the methylation array and bisulfite sequencing results revealed 3 regions surrounding the transcriptional start site of PLAC8 gene whose CpG methylation negatively correlate with RNA expression in samples from control and GDM ECFCs. In contrast, a CpG island is fully unmethylated in both control and GDM ECFCs. The discovery of CpG sites whose methylation correlates with PLAC8 mRNA expression in ECFCs is consistent with the hypothesis that intrauterine exposure to GDM results in epigenetic changes. Analysis of methylation at this site could be used as a biomarker for children of mothers with GDM who may be at risk for disease later in life. Using bisulfite pyrosequencing, we are currently developing assays to quickly determine if methylation of the PLAC8 putative promoter region is altered in cord blood mononuclear cells obtained from GDM or healthy control pregnancies. We are also investigating the role of methylation in regulating PLAC8 RNA expression, determining if there is altered histone modifications and transcription factor binding in these regions, and examining other genes that may comprise a molecular signature of ECFC dysfunction

Differential cross sections and recoil polarizations for the reaction gamma p -> K+ Sigma0

High-statistics measurements of differential cross sections and recoil polarizations for the reaction $\gamma p \rightarrow K^+ \Sigma^0$ have been obtained using the CLAS detector at Jefferson Lab. We cover center-of-mass energies ($\sqrt{s}$) from 1.69 to 2.84 GeV, with an extensive coverage in the $K^+$ production angle. Independent measurements were made using the $K^{+}p\pi^{-}$($\gamma$) and $K^{+}p$($\pi^-, \gamma$) final-state topologies, and were found to exhibit good agreement. Our differential cross sections show good agreement with earlier CLAS, SAPHIR and LEPS results, while offering better statistical precision and a 300-MeV increase in $\sqrt{s}$ coverage. Above $\sqrt{s} \approx 2.5$ GeV, $t$- and $u$-channel Regge scaling behavior can be seen at forward- and backward-angles, respectively. Our recoil polarization ($P_\Sigma$) measurements represent a substantial increase in kinematic coverage and enhanced precision over previous world data. At forward angles we find that $P_\Sigma$ is of the same magnitude but opposite sign as $P_\Lambda$, in agreement with the static SU(6) quark model prediction of $P_\Sigma \approx -P_\Lambda$. This expectation is violated in some mid- and backward-angle kinematic regimes, where $P_\Sigma$ and $P_\Lambda$ are of similar magnitudes but also have the same signs. In conjunction with several other meson photoproduction results recently published by CLAS, the present data will help constrain the partial wave analyses being performed to search for missing baryon resonances.Comment: 23 pages, 17 figure

Differential cross sections and spin density matrix elements for the reaction gamma p -> p omega

High-statistics differential cross sections and spin density matrix elements for the reaction gamma p -> p omega have been measured using the CLAS at Jefferson Lab for center-of-mass (CM) energies from threshold up to 2.84 GeV. Results are reported in 112 10-MeV wide CM energy bins, each subdivided into cos(theta_CM) bins of width 0.1. These are the most precise and extensive omega photoproduction measurements to date. A number of prominent structures are clearly present in the data. Many of these have not previously been observed due to limited statistics in earlier measurements

Near-threshold Photoproduction of Phi Mesons from Deuterium

We report the first measurement of the differential cross section on $\phi$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections $\frac{d\sigma}{dt}$ for the initial photon energy from 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. This experiment establishes a baseline for a future experimental search for an exotic $\phi$-N bound state from heavier nuclear targets utilizing subthreshold/near-threshold production of $\phi$ mesons

Coherent Photoproduction of pi^+ from 3^He

We have measured the differential cross section for the $\gamma$$^3$He$\rightarrow \pi^+ t$ reaction. This reaction was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid $^3$He target. The differential cross sections for the $\gamma$$^3$He$\rightarrow \pi^+ t$ reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.Comment: 11 pages, 16 figure