Anisotropic Zeeman Splitting in YbNi4P2

The electronic structure of heavy-fermion materials is highly renormalised at low temperatures with localised moments contributing to the electronic excitation spectrum via the Kondo effect. Thus, heavy-fermion materials are very susceptible to Lifshitz transitions due to the small effective Fermi energy arising on parts of the renormalised Fermi surface. Here, we study Lifshitz transitions that have been discovered in YbNi4P2 in high magnetic fields. We measure the angular dependence of the critical fields necessary to induce a number of Lifshitz transitions and find it to follow a simple Zeeman-shift model with anisotropic g-factor. This highlights the coherent nature of the heavy quasiparticles forming a renormalised Fermi surface. We extract information on the orientation of the Fermi surface parts giving rise to the Lifshitz transitions and we determine the anisotropy of the effective g-factor to be $\eta \approx 3.8$ in good agreement with the crystal field scheme of YbNi4P2.Comment: 10 pages, 5 figures, prepared for resubmission to SciPos

Activation of PKR by Bunyamwera virus is independent of the viral interferon antagonist NSs

Double-stranded RNA (dsRNA) is a by-product of viral RNA polymerase activity, and its recognition is one mechanism by which the innate immune system is activated. Cellular responses to dsRNA include induction of alpha/beta interferon (IFN) synthesis and activation of the enzyme PKR, which exerts its antiviral effect by phosphorylating the eukaryotic initiation factor eIF-2 alpha, thereby inhibiting translation. We have recently identified the nonstructural protein NSs of Bunyamwera virus (BUNV), the prototype of the family Bunyaviridae, as a virulence factor that blocks the induction of IFN by dsRNA. Here, we investigated the potential of NSs to inhibit PKR. We show that wild-type (wt) BUNV that expresses NSs triggered PKR-dependent phosphorylation of eIF-2 alpha to levels similar to those of a recombinant virus that does not express NSs (BUNdelNSs virus). Furthermore, the sensitivity of viruses in cell culture to IFN was independent of PKR and was not determined by NSs. PKR knockout mice, however, succumbed to infection approximately 1 day earlier than wt mice or mice deficient in expression of RNase L, another dsRNA-activated antiviral enzyme. Our data indicate that (i) bunyaviruses activate PKR, but are only marginally sensitive to its antiviral effect, and (ii) NSs is different from other IFN antagonists, since it inhibits dsRNA-dependent IFN induction but has no effect on the dsRNA-activated PKR and RNase L systems

Break up of heavy fermions at an antiferromagnetic instability

We present results of high-resolution, low-temperature measurements of the Hall coefficient, thermopower, and specific heat on stoichiometric YbRh2Si2. They support earlier conclusions of an electronic (Kondo-breakdown) quantum critical point concurring with a field induced antiferromagnetic one. We also discuss the detachment of the two instabilities under chemical pressure. Volume compression/expansion (via substituting Rh by Co/Ir) results in a stabilization/weakening of magnetic order. Moderate Ir substitution leads to a non-Fermi-liquid phase, in which the magnetic moments are neither ordered nor screened by the Kondo effect. The so-derived zero-temperature global phase diagram promises future studies to explore the nature of the Kondo breakdown quantum critical point without any interfering magnetism.Comment: minor changes, accepted for publication in JPS

On Silicon Carbide Grains as the Carrier of the 21 Micron Emission Feature in Post-Asymptotic Giant Branch Stars

The mysterious 21mu emission feature seen in 12 proto-planetary nebulae (PPNe) remains unidentified since its first detection in 1989. Over a dozen of candidate materials have been proposed within the past decade, but none of them has received general acceptance. Very recently, silicon carbide (SiC) grains with impurities were suggested to be the carrier of this enigmatic feature, based on recent laboratory data that doped SiC grains exhibit a resonance at \~21mu. This proposal gains strength from the fact that SiC is a common dust species in carbon-rich circumstellar envelopes. However, SiC dust has a strong vibrational band at ~11.3mu. We show in this Letter that in order to be consistent with the observed flux ratios of the 11.3mu feature to the 21mu feature, the band strength of the 21mu resonance has to be very strong, too strong to be consistent with current laboratory measurements. But this does not yet readily rule out the SiC hypothesis since recent experimental results have demonstrated that the 21mu resonance of doped SiC becomes stronger as the C impurity increases. Further laboratory measurements of SiC dust with high fractions of C impurity are urgently needed to test the hypothesis of SiC as the carrier of the 21mu feature.Comment: 14 pages, 3 figures, accepted for publication in ApJ

Smokers are less likely than non-smokers to seek help for a lung cancer 'alarm' symptom

BACKGROUND: The majority (>85%) of lung cancer cases are linked with smoking, and prognosis is poor because it is often diagnosed at a late stage. One contributor to late-stage diagnosis could be patient delay in help-seeking. We investigated the help-seeking behaviour of smokers and non-smokers for a recent lung cancer alarm symptom. METHODS: A health survey was sent to 4913 men and women aged >50 years through through General Practice. It included questions on symptoms experienced in the past 3 months (from a checklist), help-seeking (Yes/No) for each symptom and demographic characteristics including smoking status. Univariable and multivariable binary logistic regression analyses were used to assess the association between smoking status and help-seeking for a cough or hoarseness. RESULTS: Among 2042 participants (42% response rate), 280 (14%) reported 'cough or hoarseness' in the past 3 months; of whom 22% were current smokers. Being a smoker was associated with reduced likelihood of help-seeking (OR 0.44; 95% CI 0.23 to 0.83), even after adjusting for demographic factors (OR 0.46; 95% CI 0.21 to 1.00). CONCLUSIONS: Delay in help-seeking in smokers for a symptom that is potentially indicative of lung cancer is a cause for concern. Future research could usefully address the psychological mechanisms through which help-seeking in smokers is hindered

Electronic Structure of LuRh2Si2: "Small" Fermi Surface Reference to YbRh2Si2

We present band structure calculations and quantum oscillation measurements on LuRh2Si2, which is an ideal reference to the intensively studied quantum critical heavy-fermion system YbRh2Si2. Our band structure calculations show a strong sensitivity of the Fermi surface on the position of the silicon atoms zSi within the unit cell. Single crystal structure refinement and comparison of predicted and observed quantum oscillation frequencies and masses yield zSi = 0.379c in good agreement with numerical lattice relaxation. This value of zSi is suggested for future band structure calculations on LuRh2Si2 and YbRh2Si2. LuRh2Si2 with a full f electron shell represents the "small" Fermi surface configuration of YbRh2Si2. Our experimentally and ab initio derived quantum oscillation frequencies of LuRh2Si2 show strong differences with earlier measurements on YbRh2Si2. Consequently, our results confirm the contribution of the f electrons to the Fermi surface of YbRh2Si2 at high magnetic fields. Yet the limited agreement with refined fully itinerant local density approximation calculations highlights the need for more elaborated models to describe the Fermi surface of YbRh2Si2.Comment: 12 pages 10 figure

Worrying about wasting GP time as a barrier to help-seeking: a community-based, qualitative study

Background Worrying about wasting GP time is frequently cited as a barrier to help-seeking for cancer symptoms. Aim To explore the circumstances under which individuals feel that they are wasting GP time. Design and setting Community-based, qualitative interview studies that took place in London, the South East and the North West of England. Method Interviewees (n = 62) were recruited from a sample (n = 2042) of adults aged ≥50 years, who completed a ‘health survey’ that included a list of cancer ‘alarm’ symptoms. Individuals who reported symptoms at baseline that were still present at the 3-month follow-up (n = 271), and who had also consented to be contacted (n = 215), constituted the pool of people invited for interview. Analyses focused on accounts of worrying about wasting GP time. Results Participants were worried about wasting GP time when time constraints were visible, while dismissive interactions with their GP induced a worry of unnecessary help-seeking. Many felt that symptoms that were not persistent, worsening, or life-threatening did not warrant GP attention. Additionally, patients considered it time-wasting when they perceived attention from nurses or pharmacists to be sufficient, or when appointment structures (for example, ‘one issue per visit’) were not adhered to. Close relationships with GPs eased worries about time-wasting, while some patients saw GPs as fulfilling a service financed by taxpayers

The first night effect in multiple sclerosis patients undergoing home-based polysomnography

Background: The first night effect (FNE) is a polysomnography (PSG) habituation effect in the first of several consecutive in-laboratory PSGs (I-PSGs). The ENE is caused by the discomfort provoked by electrodes and cables and the exposure to an unfamiliar environment. A reverse ENE (RENT) with an improved sleep in the first night is characteristic of insomnia, presumably because the video PSG in the sleep laboratory leads to a decrease in the negatively toned cognitive activity. Therefore, two or more I-PSGs are required for an accurate diagnosis. Although the FNE is well documented in I-PSG, little is known about the FNE and the RFNE in home-based PSGs (H-PSGs). Methods: This is a retrospective analysis of a recently published cross-sectional study using H-PSG. Sixty-three consecutive patients suffering from multiple sclerosis (MS) were investigated by two consecutive H-PSGs without video. The differences between the first and second H-PSGs were analyzed. The patients were classified into four subgroups: no sleep disorder, insomnia, sleep-related breathing disorders (SRBDs), and periodic limb movement disorder or restless legs syndrome (PLMD/RLS). Results: MS patients suffering from insomnia showed no RFNE. MS patients with SKIM or PLMD/RLS showed no reduced sleep efficiency but significantly less slow wave sleep. Furthermore, SRBD patients showed significantly less non-rapid eye movement (N REM) sleep, and PLMD/RLS patients were significantly awake longer in the first night after sleep onset (increased wake-after-sleep-onset time) and showed a higher rapid eye movement (REM) latency. Conclusion: SRBD and PLMD/RLS patients showed a significant FNE. Two consecutive H-PSGs are required in these patients to obtain a precise hypnogram even in the ambulatory field. In MS patients suffering from insomnia, no RFNE was found, and in insomnia patients one H-PSG seems to be sufficient

D-string on near horizon geometries and infinite conformal symmetry

We show that the symmetries of effective D-string actions in constant dilaton backgrounds are directly related to homothetic motions of the background metric. In presence of such motions, there are infinitely many nonlinearly realized rigid symmetries forming a loop (or loop like) algebra. Near horizon (AdS) D3 and D1+D5 backgrounds are discussed in detail and shown to provide 2d interacting field theories with infinite conformal symmetry.Comment: 5 pages, revtex, no figures; symmetry transformations for BI action added, coupling of D-string to RR 2-form in D1-D5 background corrected; final version, to appear in Phys. Rev. Let