Selective High Impedance Surface Active Region Loading of Archimedean Spiral Antenna

We show that a significant increase in the gain and front-to-back ratio is obtained when different high impedance surface (HIS) sections are placed below the active regions of an Archimedean spiral antenna. The principle of operation is demonstrated at 3, 6, and 9 GHz for an antenna design that employs a ground plane composed of two dissimilar HISs. The unit cells of the HISs are collocated and resonant at the same frequency as the 3- and 6-GHz active regions of the wideband spiral. It is shown that the former HIS must also be designed to resonate at 9 GHz to avoid the generation of a boresight null that occurs because the structure is physically large enough to support higher-order modes. The improvement that is obtained at each of the three frequencies investigated is shown by comparing the predicted and measured radiation patterns for the free space and HIS-backed antenna.

Near Field Enhancement and Subwavelength Imaging Using Resonantly Loaded Apertures

It is demonstrated that the electromagnetic (EM) transmission through a subwavelength or non-resonant aperture in a conductive screen can be dramatically enhanced by loading it with folded metallic strips exhibiting resonant properties. When illuminated by an EM plane wave these loaded apertures enable very tight, subwavelength, collimation of the EM power in the near field zone. We propose planar and quasi-planar resonant insertion geometries that should allow, for the first time, two-dimensional dual-polarization subwavelength field confinement along with ability to focus both electric and magnetic fields. The proposed technique for resonance transmission enhancement and near field confinement forms a basis for a new class of microwave near field imaging probe with subwavelength resolution capable of operating over a wide range of imaging distances (0.05–$0.25lambda$). Measurement results demonstrate the possibility of high contrast (more than 3 dB in amplitude and 40 degrees in phase) near field subwavelength imaging of 2D and 3D resonant and non-resonant metallic and dielectric targets in free space and in moderately lossy layered media.

Vector representation of directional modulation transmitters

Directional Modulation (DM) is a recently proposed technique for securing wireless communication. In this paper we point out that modulation-directionality is a consequence of varying the beamforming network, either in baseband or in the RF stage, at the information rate In order to formalize and extend on previous analysis and synthesis methods a new theoretical treatment using vector representations of directional modulation (DM) systems is introduced and used to obtain the necessary and sufficient con

A 2.2 GHz High-Efficiency Third-Harmonic-Peaking Class-EF Power Amplifier

This paper presents the design and implementation of a low-voltage-stress Class-EF power amplifier (PA) with extended maximum operating frequency, named as ‘third-harmonic-peaking Class-EF PA’. A novel transmission-line load network is proposed to meet the Class-EF impedance requirements at the fundamental, all even harmonics, and third harmonic components. It also provides an impedance matching to a 50 Ω load. A more effective λ/8 open- and shorted-stub network is deployed at the drain of the transistor replacing the traditional λ/4 transmission line. Implemented using GaN HEMTs, the PA delivered 39.2 dBm output power with 80.5% drain efficiency and 71% PAE at 2.22 GHz.

GWAS identifies an NAT2 acetylator status tag single nucleotide polymorphism to be a major locus for skin fluorescence

Skin fluorescence (SF) is a non-invasive marker of AGEs and is associated with the long-term complications of diabetes. SF increases with age and is also greater among individuals with diabetes. A familial correlation of SF suggests that genetics may play a role. We therefore performed parallel genome-wide association studies of SF in two cohorts.

Predictors and dynamics of postpartum relapses in women with multiple sclerosis

Several studies have shown that pregnancy reduces multiple sclerosis (MS) relapses, which increase in the early postpartum period. Postpartum relapse risk has been predicted by pre-pregnancy disease activity in some studies.

Genome-wide meta-analysis identifies 11 new loci for anthropometric traits and provides insights into genetic architecture

Approaches exploiting trait distribution extremes may be used to identify loci associated with common traits, but it is unknown whether these loci are generalizable to the broader population. In a genome-wide search for loci associated with the upper versus the lower 5th percentiles of body mass index, height and waist-to-hip ratio, as well as clinical classes of obesity, including up to 263,407 individuals of European ancestry, we identified 4 new loci (IGFBP4, H6PD, RSRC1 and PPP2R2A) influencing height detected in the distribution tails and 7 new loci (HNF4G, RPTOR, GNAT2, MRPS33P4, ADCY9, HS6ST3 and ZZZ3) for clinical classes of obesity. Further, we find a large overlap in genetic structure and the distribution of variants between traits based on extremes and the general population and little etiological heterogeneity between obesity subgroups.

Outgassing Behavior of C/2012 S1 (ISON) from 2011 September to 2013 June

We report photometric observations for comet C/2012 S1 (ISON) obtained during the time period immediately after discovery (r = 6.28 AU) until it moved into solar conjunction in mid-2013 June using the UH2.2 m, and Gemini North 8 m telescopes on Mauna Kea, the Lowell 1.8 m in Flagstaff, the Calar Alto 1.2 m telescope in Spain, the VYSOS-5 telescopes on Mauna Loa Hawaii and data from the CARA network. Additional pre-discovery data from the Pan STARRS1 survey extends the light curve back to 2011 September 30 (r = 9.4 AU). The images showed a similar tail morphology due to small micron sized particles throughout 2013. Observations at submillimeter wavelengths using the James Clerk Maxwell Telescope on 15 nights between 2013 March 9 (r = 4.52 AU) and June 16 (r = 3.35 AU) were used to search for CO and HCN rotation lines. No gas was detected, with upper limits for CO ranging between 3.5-4.5 × 1027 molecules s-1. Combined with published water production rate estimates we have generated ice sublimation models consistent with the photometric light curve. The inbound light curve is likely controlled by sublimation of CO2. At these distances water is not a strong contributor to the outgassing. We also infer that there was a long slow outburst of activity beginning in late 2011 peaking in mid-2013 January (r ~ 5 AU) at which point the activity decreased again through 2013 June. We suggest that this outburst was driven by CO injecting large water ice grains into the coma. Observations as the comet came out of solar conjunction seem to confirm our models.

The effect of inhaled IFN-β on worsening of asthma symptoms caused by viral infections. a randomized trial

Rationale: Ex vivo, bronchial epithelial cells from people with asthma are more susceptible to rhinovirus infection caused by deficient induction of the antiviral protein, IFN-b. Exogenous IFN-b restores antiviral activity.

Objectives: To compare the efficacy and safety of inhaled IFN-b with placebo administered to people with asthma after onset of cold symptoms to prevent or attenuate asthma symptoms caused by respiratory viruses.

Methods: A total of 147 people with asthma on inhaled corticosteroids (British Thoracic Society Steps 2–5), with a history of virus-associated exacerbations, were randomized to 14-day treatment with inhaled IFN-b (n = 72) or placebo (n = 75) within 24 hours of developing cold symptoms and were assessed clinically, with relevant samples collected to assess virus infection and antiviral responses.

Measurements and Main Results: A total of 91% of randomized patients developed a defined cold. In this modified intention-to-treat population, asthma symptoms did not get clinically significantly worse
(mean change in six-item Asthma Control Questionnaire ,0.5) and IFN-b treatment had no significant effect on this primary endpoint, although it enhanced morning peak expiratory flow recovery (P = 0.033), reduced the need for additional treatment, and boosted innate immunity as assessed by blood and sputum biomarkers. In an exploratory analysis of the subset ofmore difficult-to-treat, Step 4-5 peoplewith asthma (n = 27 IFN-b; n = 31 placebo), Asthma Control Questionnaire-6 increased significantly on placebo; this was prevented by IFN-b (P = 0.004).

Conclusions: Although the trial did not meet its primary endpoint, it suggests that inhaled IFN-b is a potential treatment for virus-induced deteriorations of asthma in difficult-to-treat people with asthma and supports the needforfurther, adequately powered, trialsin this population. Clinical trial registered with www.clinicaltrials.gov (NCT 01126177).