Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are likely caused by dust lifted high above the disk plane; this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.Comment: 20 pages, 11 figures, accepted for publication in Astronomy & Astrophysic

Suppression of Antiferromagnetic Order by Light Hole Doping in La_2Cu_{1-x}Li_xO_4: A ^{139}La NQR Study

^{139}La nuclear quadrupole resonance measurements in lightly doped La_2Cu_{1-x}Li_xO_4 have been performed to reveal the dependence of the magnetic properties of the antiferromagnetic CuO_2 planes on the character of the doped holes and their interactions with the dopant. A detailed study shows that the magnetic properties are remarkably insensitive to the character of the dopant impurity. This indicates that the added holes form previously unrecognized collective structures.Comment: 4 pages, 3 figures. Slightly modified version, as accepted for publication in Physical Review Letter

Spin Dynamics in the LTT Phase of ~1/8 Doped Single Crystal La_{1.67}Eu_{0.2}Sr_{0.13}CuO_4

We present La and Cu NMR relaxation measurements in single crystal La_{1.67}Eu_{0.2}Sr_{0.13}CuO_4. A strong peak in the La spin-lattice relaxation rate observed in the spin ordered state is well-described by the BPP mechanism[1] and arises from continuous slowing of electronic spin fluctuations with decreasing temperature; these spin fluctuations exhibit XY-like anisotropy in the ordered state. The spin pseudogap is enhanced by the static charge-stripe order in the LTT phase.Comment: Four pages, three figure

Evidence for Strange Quark Contributions to the Nucleon's Form Factors at Q2Q^2 = 0.108 (GeV/c)2^2

We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of $Q^2$ = \Qsquare (GeV/c)$^2$ and at a forward electron scattering angle of 30$^\circ < \theta_e < 40^\circ$. The measured asymmetry is $A_{LR}(\vec{e}p)$ = (\Aphys $\pm$ \Deltastat$_{stat}$ $\pm$ \Deltasyst$_{syst}$) $\times$ 10$^{-6}$. The expectation from the Standard Model assuming no strangeness contribution to the vector current is A$_0$ = (\Azero $\pm$ \DeltaAzero) $\times$ 10$^{-6}$. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher $Q^2$. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be $G_E^s$ + \FakGMs $G_M^s$ = \GEsGMs $\pm$ \DeltaGEsGMs at $Q^2$ = \Qsquare (GeV/c)$^2$. As in our previous measurement at higher momentum transfer for $G_E^s$ + 0.230 $G_M^s$, we again find the value for $G_E^s$ + \FakGMs $G_M^s$ to be positive, this time at an improved significance level of 2 $\sigma$.Comment: 4 pages, 3 figure

Charge degree of freedom and single-spin fluid model in YBa_2Cu_4O_8

We present a 17O nuclear magnetic resonance study in the stoichiometric superconductor YBa_2Cu_4O_8. A double irradiation method enables us to show that, below around 180 K, the spin-lattice relaxation rate of plane oxygen is not only driven by magnetic, but also significantly by quadrupolar fluctuations, i.e. low-frequency charge fluctuations. In the superconducting state, on lowering the temperature, the quadrupolar relaxation diminishes faster than the magnetic one. These findings show that, with the opening of the pseudo spin gap, a charge degree of freedom of mainly oxygen character is present in the electronic low-energy excitation spectrum.Comment: 4 pages, 3 figures, REVTE

New strategies and designs in pancreatic cancer research: consensus guidelines report from a European expert panel

Although the treatment of pancreatic ductal adenocarcinoma (PDAC) remains a huge challenge, it is entering a new era with the development of new strategies and trial designs. Because there is an increasing number of novel therapeutic agents and potential combinations available to test in patients with PDAC, the identification of robust prognostic and predictive markers and of new targets and relevant pathways is a top priority as well as the design of adequate trials incorporating molecular-driven hypothesis. We presently report a consensus strategy for research in pancreatic cancer that was developed by a multidisciplinary panel of experts from different European institutions and collaborative groups involved in pancreatic cancer. The expert panel embraces the concept of exploratory early proof of concept studies, based on the prediction of response to novel agents and combinations, and randomised phase II studies permitting the selection of the best therapeutic approach to go forward into phase III, where the recommended primary end point remains overall survival. Trials should contain as many translational components as possible, relying on standardised tissue and blood processing and robust biobanking, and including dynamic imaging. Attention should not only be paid to the pancreatic cancer cells but also to microenvironmental factors and stem/stellate cell

Measurement of Strange Quark Contributions to the Nucleon's Form Factors at Q^2=0.230 (GeV/c)^2

We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a $Q^2$ of 0.230 (GeV/c)^2 and a scattering angle of \theta_e = 30^o - 40^o. Using a large acceptance fast PbF_2 calorimeter with a solid angle of \Delta\Omega = 0.62 sr the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A_{phys} =(-5.44 +- 0.54_{stat} +- 0.27_{\rm sys}) 10^{-6}. The Standard Model expectation assuming no strangeness contributions to the vector form factors is $A_0=(-6.30 +- 0.43) 10^{-6}$. The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G^s_E + 0.225 G^s_M = 0.039 +- 0.034 or F^s_1 + 0.130 F^s_2 = 0.032 +- 0.028.Comment: 5 pages, 3 figures, submitted to Phys. Rev. Letters on Dec 11, 200

Medical graduates’ preparedness to practice: A comparison of undergraduate medical school training

Background: There is evidence that newly qualified doctors do not feel prepared to start work. This study examined views of first year Foundation doctors (F1s) regarding how prepared they felt by their undergraduate medical education for skills required during the first Foundation training year in relation to their type of training. Method: One-hundred and eighty two F1s completed a questionnaire during their first rotation of Foundation training. Analysis was conducted by type of medical school training: Problem-Based Learning (PBL), Traditional or Reformed. Results: F1s from medical schools with a PBL curriculum felt better prepared for tasks associated with communication and team working, and paperwork than graduates from the other medical school types; but the majority of F1s from all three groups felt well prepared for most areas of practice. Less than half of graduates in all three groups felt well prepared to deal with a patient with neurological/visual problems; write referral letters; understand drug interactions; manage pain; and cope with uncertainty. F1s also indicated that lack of induction or support on starting work was affecting their ability to work in some areas. Conclusions: Whilst F1s from medical schools with a PBL curriculum did feel better prepared in multiple areas compared to graduates from the other medical school types, specific areas of unpreparedness related to undergraduate and postgraduate medical training were identified across all F1s. These areas need attention to ensure F1s are optimally prepared for starting work

Knowledge and attitude of final - year medical students in Germany towards palliative care - an interinstitutional questionnaire-based study

<p>Abstract</p> <p>Background</p> <p>To care for terminally ill and dying patients requires a thorough medical education, encompassing skills, knowledge, and attitudes in the field of palliative care. Undergraduate medical students in Germany will receive mandatory teaching in palliative care in the near future driven by recent changes in the Medical Licensure Act. Before new curricula can be implemented, the knowledge of medical students with respect to palliative care, their confidence to handle palliative care situations correctly, their therapeutic attitude, and their subjective assessment about previous teaching practices have to be better understood.</p> <p>Method</p> <p>We designed a composite, three-step questionnaire (self estimation of confidence, knowledge questions, and opinion on the actual and future medical curriculum) conducted online of final - year medical students at two universities in Germany.</p> <p>Results</p> <p>From a total of 318 enrolled students, 101 responded and described limited confidence in dealing with specific palliative care issues, except for pain therapy. With regard to questions examining their knowledge base in palliative care, only one third of the students (33%) answered more than half of the questions correctly. Only a small percentage of students stated they had gained sufficient knowledge and experience in palliative care during their studies, and the vast majority supported the introduction of palliative care as a mandatory part of the undergraduate curriculum.</p> <p>Conclusion</p> <p>This study identifies medical students' limited confidence and knowledge base in palliative care in 2 German universities, and underlines the importance of providing a mandatory palliative care curriculum.</p