Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves

We propose a generalization of the two-dimensional eikonal-limit cloak derived from a conformal transformation to three dimensions. The proposed cloak is a spherical shell composed of only isotropic media; it operates in the transmission mode and requires no mirror or ground plane. Unlike the well-known omnidirectional spherical cloaks, it may reduce visibility of an arbitrary object only for a very limited range of observation angles. In the short-wavelength limit, this cloaking structure restores not only the trajectories of incident rays, but also their phase, which is a necessary ingredient to complete invisibility. Both scalar-wave (acoustic) and transverse vector-wave (electromagnetic) versions are presented.Comment: 17 pages, 12 figure

Agricultural Education Teacher Candidates’ Reflection on the 15-Week Clinical Teaching Internship: A Collective Case Study

This collective case study explored the integration of video reflection during the 15-week clinical teaching internship at three distinct points in time. Weeks three, seven, and 11 were investigated to determine if the integration of video reflection improved the quality of teacher candidate reflection and to gauge teacher candidates’ views on agricultural education during the clinical teaching internship. Four overarching themes emerged from the video reflections: establishing roles as a teacher, teaching and learning, balance, and coming full circle. Throughout the internship, candidates expressed a deeper understanding of teaching within the three-component model of school-based agricultural education (SBAE). We recommend the use of video reflection during the student teaching internship to expand the depth of reflection and feeling of community among the cohort. Overall, the addition of the video reflection process has provided an efficient and effective tool that allows teacher candidates to make meaning of their experience

Seasonal versus Perennial Allergic Rhinitis: Drug and Medical Resource Use Patterns

AbstractBackgroundThere are no published studies that have compared the medical costs of patients with seasonal and perennial allergic rhinitis symptomatology.ObjectivesThe objectives of this study were to develop an algorithm for classifying patients into seasonal and perennial groups based on their patterns of allergy medication use and then compare the epidemiology and economics of the two groups.MethodsData for the study were obtained from the 1996 to 1998 MarketScan databases containing linked inpatient, outpatient, and pharmaceutical claims for approximately 2 million covered lives annually. Patients were classified into seasonal allergic rhinitis (SAR) or perennial allergic rhinitis (PAR) groups based on their pattern of allergy medication use over the course of 1 year and then compared using descriptive methods.ResultsSeventy-nine percent of the total study sample (80,534 allergy patients) was classified as SAR and 21% as PAR. PAR patients were found to have higher mean levels of allergy-related outpatient payments ($568 vs.$471) and higher mean costs for second-generation antihistamines ($552 vs.$162). PAR patients also had higher levels of comorbidities (asthma, sinusitis, depression, and migraine), higher numbers of concomitant medications (multiple second-generation antihistamines, nasal steroids, other antihistamines, asthma medications, and ophthalmic decongestants), and more immunization encounters.ConclusionsApproximately 21% of allergic rhinitis patients have perennial symptoms as reflected in their patterns of medication use. Perennial patients have significantly higher allergy-related health-care costs and rates of comorbidities and greater use of concomitant medications. These distinct clinical and resource use profiles may have implications for therapy choices in the cost-effective management of perennial allergic rhinitis patients

Inferring the parallax of Westerlund 1 from Gaia DR2

Westerlund 1 (Wd1) is potentially the largest star cluster in the Galaxy. That designation critically depends upon the distance to the cluster, yet the cluster is highly obscured, making luminosity-based distance estimates difficult. Using {\it Gaia} Data Release 2 (DR2) parallaxes and Bayesian inference, we infer a parallax of $0.35^{+0.07}_{-0.06}$ mas corresponding to a distance of $2.6^{+0.6}_{-0.4}$ kpc. To leverage the combined statistics of all stars in the direction of Wd1, we derive the Bayesian model for a cluster of stars hidden among Galactic field stars; this model includes the parallax zero-point. Previous estimates for the distance to Wd1 ranged from 1.0 to 5.5 kpc, although values around 5 kpc have usually been adopted. The {\it Gaia} DR2 parallaxes reduce the uncertainty from a factor of 3 to 18\% and rules out the most often quoted value of 5 kpc with 99\% confidence. This new distance allows for more accurate mass and age determinations for the stars in Wd1. For example, the previously inferred initial mass at the main-sequence turn-off was around 40 M$_{\odot}$; the new {\it Gaia} DR2 distance shifts this down to about 22 M$_{\odot}$. This has important implications for our understanding of the late stages of stellar evolution, including the initial mass of the magnetar and the LBV in Wd1. Similarly, the new distance suggests that the total cluster mass is about four times lower than previously calculated.Comment: 14 pages, 10 figure

On the Progenitor System of the Type Iax Supernova 2014dt in M61

We present pre-explosion and post-explosion Hubble Space Telescope images of the Type Iax supernova (SN Iax) 2014dt in M61. After astrometrically aligning these images, we do not detect any stellar sources at the position of the SN in the pre-explosion images to relatively deep limits (3 sigma limits of M_F438W > -5.0 mag and M_F814W > -5.9 mag). These limits are similar to the luminosity of SN 2012Z's progenitor system (M_F435W = -5.43 +/- 0.15 and M_F814W = -5.24 +/- 0.16 mag), the only probable detected progenitor system in pre-explosion images of a SN Iax, and indeed, of any white dwarf supernova. SN 2014dt is consistent with having a C/O white-dwarf primary/helium-star companion progenitor system, as was suggested for SN 2012Z, although perhaps with a slightly smaller or hotter donor. The data are also consistent with SN 2014dt having a low-mass red giant or main-sequence star companion. The data rule out main-sequence stars with M_init > 16 M_sun and most evolved stars with M_init > 8 M_sun as being the progenitor of SN 2014dt. Hot Wolf-Rayet stars are also allowed, but the lack of nearby bright sources makes this scenario unlikely. Because of its proximity (D = 12 Mpc), SN 2014dt is ideal for long-term monitoring, where images in ~2 years may detect the companion star or the luminous bound remnant of the progenitor white dwarf.Comment: 5 pages, 3 figures, submitted to ApJ

The Journal of Comorbidity affiliates with the Society for Academic Primary Care

No abstract available

Vaccinia virus protein A46R targets multiple Toll-like-interleukin-1 receptor adaptors and contributes to virulence

Viral immune evasion strategies target key aspects of the host antiviral response. Recently, it has been recognized that Toll-like receptors (TLRs) have a role in innate defense against viruses. Here, we define the function of the vaccinia virus (VV) protein A46R and show it inhibits intracellular signalling by a range of TLRs. TLR signalling is triggered by homotypic interactions between the Toll-like-interleukin-1 resistance (TIR) domains of the receptors and adaptor molecules. A46R contains a TIR domain and is the only viral TIR domain-containing protein identified to date. We demonstrate that A46R targets the host TIR adaptors myeloid differentiation factor 88 (MyD88), MyD88 adaptor-like, TIR domain-containing adaptor inducing IFN-beta (TRIF), and the TRIF-related adaptor molecule and thereby interferes with downstream activation of mitogen-activated protein kinases and nuclear factor kappaB. TRIF mediates activation of interferon (IFN) regulatory factor 3 (IRF3) and induction of IFN-beta by TLR3 and TLR4 and suppresses VV replication in macrophages. Here, A46R disrupted TRIF-induced IRF3 activation and induction of the TRIF-dependent gene regulated on activation, normal T cell expressed and secreted. Furthermore, we show that A46R is functionally distinct from another described VV TLR inhibitor, A52R. Importantly, VV lacking the A46R gene was attenuated in a murine intranasal model, demonstrating the importance of A46R for VV virulence

Galactic Twins of the Ring Nebula Around SN1987A and a Possible LBV-like Phase for Sk-69 202

Some core-collapse supernovae show clear signs of interaction with dense circumstellar material that often appears to be non-spherical. Circumstellar nebulae around supernova progenitors provide clues to the origin of that asymmetry in immediate pre-supernova evolution. Here I discuss outstanding questions about the formation of the ring nebula around SN1987A and some implications of similar ring nebulae around Galactic B supergiants. Several clues hint that SN1987A's nebula may have been ejected in an LBV-like event, rather than through interacting winds in a transition from a red supergiant to a blue supergiant.Comment: 2 pages, to appear in procedings of "Massive stars: fundamental parameters and circumstellar interactions", conference in honor of Virpi Niemela's 70th birthda

Does the worsening galactic cosmic radiation environment observed by CRaTER preclude future manned deep space exploration?

Abstract The Sun and its solar wind are currently exhibiting extremely low densities and magnetic field strengths, representing states that have never been observed during the space age. The highly abnormal solar activity between cycles 23 and 24 has caused the longest solar minimum in over 80 years and continues into the unusually small solar maximum of cycle 24. As a result of the remarkably weak solar activity, we have also observed the highest fluxes of galactic cosmic rays in the space age and relatively small solar energetic particle events. We use observations from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter to examine the implications of these highly unusual solar conditions for human space exploration. We show that while these conditions are not a show stopper for long-duration missions (e.g., to the Moon, an asteroid, or Mars), galactic cosmic ray radiation remains a significant and worsening factor that limits mission durations. While solar energetic particle events in cycle 24 present some hazard, the accumulated doses for astronauts behind 10 g/cm2 shielding are well below current dose limits. Galactic cosmic radiation presents a more significant challenge: the time to 3% risk of exposure-induced death (REID) in interplanetary space was less than 400 days for a 30 year old male and less than 300 days for a 30 year old female in the last cycle 23–24 minimum. The time to 3% REID is estimated to be ∼20% lower in the coming cycle 24–25 minimum. If the heliospheric magnetic field continues to weaken over time, as is likely, then allowable mission durations will decrease correspondingly. Thus, we estimate exposures in extreme solar minimum conditions and the corresponding effects on allowable durations