Experimental Demonstration of Fermi Surface Effects at Filling Factor 5/2

Using small wavelength surface acoustic waves (SAW) on ultra-high mobility heterostructures, Fermi surface properties are detected at 5/2 filling factor at temperatures higher than those at which the quantum Hall state forms. An enhanced conductivity is observed at 5/2 by employing sub 0.5 micron wavelength SAW, indicating a quasiparticle mean-free-path substantially smaller than that in the lowest Landau level. These findings are consistent with the presence of a filled Fermi sea of composite fermions, which may pair at lower temperatures to form the 5/2 ground state.Comment: 11 pages, 4 figure

A Fermi Fluid Description of the Half-Filled Landau Level

We present a many-body approach to calculate the ground state properties of a system of electrons in a half-filled Landau level. Our starting point is a simplified version of the recently proposed trial wave function where one includes the antisymmetrization operator to the bosonic Laughlin state. Using the classical plasma analogy, we calculate the pair-correlation function, the static structure function and the ground state energy in the thermodynamic limit. These results are in good agreement with the expected behavior at $\nu=\frac12$.Comment: 4 pages, REVTEX, and 4 .ps file

Current Path Properties of the Transport Anisotropy at Filling Factor 9/2

To establish the presence and orientation of the proposed striped phase in ultra-high mobility 2D electron systems at filling factor 9/2, current path transport properties are determined by varying the separation and allignment of current and voltage contacts. Contacts alligned orthogonal to the proposed intrinsic striped phase produce voltages consistent with current spreading along the stripes; current driven along the proposed stripe direction results in voltages consistent with channeling along the stripes. Direct comparison is made to current spreading/channeling properties of artificially induced 1D charge modulated systems, which indicates the 9/2 direction.Comment: 10 pages, 4 figure

Stability and effective masses of composite-fermions in the first and second Landau Level

We propose a measure of the stability of composite fermions (CF's) at even-denominator Landau-level filling fractions. Assuming Landau-level mixing effects are not strong, we show that the CF liquid at $\nu=2+1/2$ in the $n=1$ Landau level cannot exist and relate this to the absence of a hierarchy of incompressible states for filling fractions $2+1/3 < \nu < 2+2/3$. We find that a polarized CF liquid should exist at $\nu=2+1/4$. We also show that, for CF states, the variation with system size of the ground state energy of interacting electrons follows that for non-interacting particles in zero magnetic field. We use this to estimate the CF effective masses.Comment: 9 pages, Revtex, PSIZ-TP-940

Sequence of the RAG1 and RAG2 Intergenic Region in Zebrafish (Danio rerio)

The recombination activating genes, rag1 and rag2 are essential for the rearrangement of antigen receptor V, D, and J gene segments (Oettinger et al., 1990, Mombaerts et al., 1992; Sehatz and Oettinger, 1992; Shinkai et al., 1992). Both genes are found in all species that are known to rearrange their antigenspecific receptors. The coding regions as well as the genomic organization of the rag locus are highly conserved throughout evolution. Rag1 and rag2, which are convergently transcribed, are separated by an intergenic region of DNA that varies in size among species, being, for example, about 11 kb in the human (Homo sapiens), 8 kb in the mouse (Mus musculus), 5.2 kb in the frog (Xenopus laevis), 2.8 kb in the rainbow trout (Oncorhynchus mykiss) (Oettinger et al., 1990; Ichicara et al., 1992; Greenhalgh et al., 1993; Greenhalgh and Steiner., 1995; Hansen and Kaattari, 1996), and 2.6 kb in the zebrafish (Danio rerio).National Institutes of Health (U.S.) (Grant 2R01 AI08054)National Institutes of Health (U.S.) (Grant 5T32 AI07436)National Institutes of Health (U.S.) (Grant 1F32 AI09072

Long-term use of multivitamins and risk of colorectal adenoma in women

Background: Use of multivitamins may reduce the risk of colorectal adenoma, but the duration of use needed is unclear. Methods: We prospectively examined years of multivitamin use and risk of colorectal adenoma among 43 641 women who had a first endoscopy between 1991 and 2007 in the Nurses' Health Study II. Use of multivitamins was assessed through biennial questionnaires since 1989. Results: We documented 2277 colorectal adenoma cases. Reporting multivitamin use at any time during the study period compared with never reporting its use was associated with a reduced risk of adenoma (multivariable relative risk (RR)=0.86, 95% confidence interval (CI): 0.76–0.97). There was no clear trend with duration of multivitamin use: years of use compared with never use, ⩽4 years (RR=0.84, 95% CI: 0.74–0.96), 5–9 years (RR=0.89, 95% CI: 0.77, 1.02), 10–14 years (RR=0.86, 95% CI: 0.74, 1.01), 15–19 years (RR=0.85, 95% CI: 0.70, 1.02), and 20–26 years (RR=0.80, 95% CI: 0.64, 1.01); (P trend=0.87). The strongest associations (years of use vs never user) were for size of adenoma: large (⩾1 cm) <4 years (RR=0.75, 95% CI: 0.58–0.96) and in alcohol users (⩾1.4 g per day) 20–26 years (RR=0.67, 95% CI: 0.49–0.91). Conclusion: Our findings suggest that use of multivitamins is associated with lower risk of colorectal adenoma, even with relatively short duration of use

Participation in a trial in the emergency situation : a qualitative study of patient experience in the UK WOLLF trial

Background Patients can struggle to make sense of trials in emergency situations. This study examines patient experience of participating in the United Kingdom, Wound management of Open Lower Limb Fractures (UK WOLLF) study, a trial of standard wound management versus Negative Pressure Wound Therapy (NPWT). Methods The aim of the study was to understand the patient’s lived experience of taking part in a trial of wound dressings. Interviews drawing on Phenomenology were undertaken with a purposive sample of 20 patients, on average 12 days into their hospital stay from July 2012–July 2013. Results The participants were vulnerable due to the emotional and physical impact of injury. They expressed their trial experience through the theme of being compromised identified in categories of being dependent, being trusting, being grateful and being without experience. Participants felt dependent on and trusted the team to make the right decisions for them and not cause them harm. Their hopes for future recovery were also invested within the expertise of the team. Despite often not being well enough to consent to the study prior to surgery, they wished to be involved as much as possible. In agreeing to take part they expressed gratitude for their care, wanted to be helpful to others and considered the trial interventions to be a small component in relation to the enormity of their injury and broader treatment. In making sense of the trial they felt they could not understand the interventions without experience of them but if they received NPWT they developed a strong technological preference for this intervention. Conclusions Patients prefer to be involved in studies within the limits of their capacity, despite not being able to provide informed consent. A variety of sources of knowledge may enable participants to feel that they have a better understanding of the interventions. Professional staff need to be aware of the situated nature of decision making where participants invest their hopes for recovery in the team

Transcriptomic Changes and the Roles of Cannabinoid Receptors and PPARγin Developmental Toxicities following Exposure to Δ\u3csup\u3e9\u3c/sup\u3e-Tetrahydrocannabinol and Cannabidiol

Human consumption of cannabinoid-containing products during early life or pregnancy is rising. However, information about the molecular mechanisms involved in early life stage Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) toxicities is critically lacking. Here, larval zebrafish (Danio rerio) were used to measure THC- and CBD-mediated changes on transcriptome and the roles of cannabinoid receptors (Cnr) 1 and 2 and peroxisome proliferator activator receptor γ(PPARγ) in developmental toxicities. Transcriptomic profiling of 96-h postfertilization (hpf) cnr+/+ embryos exposed (6 - 96 hpf) to 4 μM THC or 0.5 μM CBD showed differential expression of 904 and 1095 genes for THC and CBD, respectively, with 360 in common. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriched in the THC and CBD datasets included those related to drug, retinol, and steroid metabolism and PPAR signaling. The THC exposure caused increased mortality and deformities (pericardial and yolk sac edemas, reduction in length) in cnr1-/- and cnr2-/- fish compared with cnr+/+ suggesting Cnr receptors are involved in protective pathways. Conversely, the cnr1-/- larvae were more resistant to CBD-induced malformations, mortality, and behavioral alteration implicating Cnr1 in CBD-mediated toxicity. Behavior (decreased distance travelled) was the most sensitive endpoint to THC and CBD exposure. Coexposure to the PPARγinhibitor GW9662 and CBD in cnr+/+ and cnr2-/- strains caused more adverse outcomes compared with CBD alone, but not in the cnr1-/- fish, suggesting that PPARγplays a role in CBD metabolism downstream of Cnr1. Collectively, PPARγ, Cnr1, and Cnr2 play important roles in the developmental toxicity of cannabinoids with Cnr1 being the most critical

Density Induced Interchange of Anisotropy Axes at Half-Filled High Landau Levels

We observe density induced 90$^{\circ}$ rotations of the anisotropy axes in transport measurements at half-filled high Landau levels in the two dimensional electron system, where stripe states are proposed ($\nu$=9/2, 11/2, etc). Using a field effect transistor, we find the transition density to be $2.9\times10^{11}$cm$^{-2}$ at $\nu$=9/2. Hysteresis is observed in the vicinity of the transition. We construct a phase boundary in the filling factor-magnetic field plane in the regime $4.4<\nu<4.6$. An in-plane magnetic field applied along either anisotropy axis always stabilizes the low density orientation of the stripes.Comment: 1 revtex file, 3 eps figure