Resonant Metalenses for Breaking the Diffraction Barrier

We introduce the resonant metalens, a cluster of coupled subwavelength resonators. Dispersion allows the conversion of subwavelength wavefields into temporal signatures while the Purcell effect permits an efficient radiation of this information in the far-field. The study of an array of resonant wires using microwaves provides a physical understanding of the underlying mechanism. We experimentally demonstrate imaging and focusing from the far-field with resolutions far below the diffraction limit. This concept is realizable at any frequency where subwavelength resonators can be designed.Comment: 4 pages, 3 figure

Observations of Extremely Cool Stars

As one part of a program of infrared astronomy carried on at the California Institute of Technology, a survey of the sky in two infrared spectral ranges, 0.68-0.92 μand 2.01- 2.41 μ, is being carried out. The motivation for such a survey is to obtain an unbiased census of objects that emit in the 2.0-2.5-μ atmospheric window; this will, of course, include many ordinary stars, but it might also reveal many potentially interesting objects that would not be included in an a priori selection of objects to be measured. In fact, a number of strikingly red stars have already been found. Since most of these "superred" stars occur in the Milky Way, interstellar reddening may be of some consequence; but in at least a few cases the stars seem to be intrinsically extremely red. These preliminary results seem of sufficient interest to merit brief description at this time

Sweet versus sour cream butter

The objects of the work herein described were to compare the sweet-cream and the sour-cream methods of butter-making, with reference to the following points: 1. Relative losses of butter fat. 2. Relative amounts of butter produced. 3. Relative keeping qualities of the butter. 4. Relative amounts of casein in the butter. The work was done between January 13 and April 8, 1892

Sweet versus ripened cream butter

The experiments here described are similar to those described in Bulletin No. 18, but differ from them in that the cream is here ripened for a shorter time. Ia each trial a quantity of thoroughly mixed cream, fresh from the separator, was divided into two parts, one of which was churned within a few hours, while still sweet; the other the next day after ripening (at about 60° F.) for 17 to 21 hours. Salt and color were proportionately the same in all cases

The role of selenium supplementation in cardiovascular disease prevention: an in vitro study to identify the molecular mechanism(s).

Obesity is a worldwide epidemic, with two thirds of the UK population either overweight or obese (body mass index (BMI) 25–29·9 and >30 kg/m2 respectively). Obesity is characterised by systemic oxidative stress (OS), which itself results from chronically high levels of reactive oxidative species (ROS) and reduced antioxidant status. OS is considered to play a key role in cardiovascular disease (CVD) development by initiating atherosclerosis. In particular, increased monocyte ROS generation instigates atherosclerotic plaque formation by increasing the recruitment, binding and transmigration of monocytes across arterial endothelial cells into the arterial wall. An increased intake of dietary antioxidants or up-regulation of endogenous antioxidant enzymes may counteract this OS state and therefore lower CVD risk. Selenium is an essential dietary micronutrient which is incorporated within the catalytic site of endogenous antioxidant Glutathione Peroxidase (GPx) enzymes and protects cells from OS and consequent cell damage. There is, however, a lack of knowledge concerning both the effect of selenium supplementation in an OS state representative of sedentary overweight/obese individuals and the mechanisms involved. The aim of this work was to investigate the effect of selenium supplementation in modulating, in vitro, monocyte cell viability, ROS generation and antioxidant enzymes gene expression (GPx1/GPx4) when under OS. U937 monocyte cells were either supplemented, or not with sodium selenite (Na2SeO3; 100nM or 200nM) and cultured for 48 hours at 37°C. Paraquat (1 mM) and S-Nitroso-N-acetyl-DL-penicillamine (0·7 mM) (SNAP) were added to cells overnight to induce OS. Cell viability was assessed via MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay, ROS generation was determined by Flow Cytometry using CM-H2DC-FDA, while GPx1/GPx4 gene expression was quantified by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). PQ/SNAP treatment significantly reduced U937 cell viability and increased ROS generation compared to untreated control U937 cells; confirming the induction of OS. Supplementation with 100nM Na2SeO3, before PQ/SNAP treatment, significantly increased cell viability by 33% (p 0·05). Furthermore, 100nM Na2SeO3 supplementation significantly reduced ROS generation by 32% (p < 0·001) in cells treated with PQ/SNAP. Correspondingly, this increased GPx1 by 146% (p < 0·01) and GPx4 gene expression by 77% (p < 0·05), when compared to un-supplemented PQ/SNAP treated cells. This study indicates that selenium supplementation may be effective in counteracting the detrimental effects of OS by significantly increasing the expression of antioxidant genes; reinforcing endogenous antioxidant protection to quench ROS generation more effectively and improve cell viability. This preliminary data, in monocyte cells, indicates that GPx1 gene expression is affected considerably more by both selenium supplementation and OS when compared with GPx4. This suggests GPx1 may play a more important role in CVD prevention, with regards to selenium supplementation in overweight/obese individuals

Infrared and Optical Measurements of the Crab Pulsar NP 0532

Observations of the pulsating component of NP 0532 at 2.2 and 1.65 μ are given. The energy density per pulse at 2.2 μ is (3.2 ± 0.4) X 10^(-31) J m^(-2) Hz^(-1) and forms a smooth continuation of the visual data

The use of a combination frequency technique to measure the surf zone bubble population

There are great benefits to sizing bubbles using a two frequency technique, which examines the appearance of sum-and-difference signals generated by the interaction between a resonant bubble pulsation and a much higher frequency imaging beam. This paper presents the results from using the technique to size bubbles in the ocean surf zone, and details the pulsation model used to calibrate the returned data such that the height of the bubble scattered signal can be related to the number of resonant bubbles of that size. It also shows how ambiguities and inaccuracies (brought on through turbulence and the substantial off-resonance nature of the signal) which affected earlier oceanic tests using the same method can be identified in the returned signal or removed from the estimate during the data processin

The effects of nonlinear wave propagation on the stability of inertial cavitation

In the context of forecasting temperature and pressure fields in high-intensity focussed ultrasound, the accuracy of predictive models is critical for the safety and efficacy of treatment. In such fields inertial cavitation is often observed. Classically, estimations of cavitation thresholds have been based on the assumption that the incident wave at the surface of a bubble was the same as in the far-field, neglecting the effect of nonlinear wave propagation. By modelling the incident wave as a solution to Burgers' equation using weak shock theory, the effects of nonlinear wave propagation on inertial cavitation are investigated using both numerical and analytical techniques. From radius-time curves for a single bubble, it is observed that there is a reduction in the maximum size of a bubble undergoing inertial cavitation and that the inertial collapse occurs earlier in contrast with the classical case. Corresponding stability thresholds for a bubble whose initial radius is slightly below the critical Blake radius are calculated. Bifurcation diagrams and frequency-response curves are presented associated with the loss of stability. The consequences and physical implications of the results are discussed with respect to the classical results.Comment: 13 pages, 5 figures, submitted to J. Phys. Conf. Se

Resonance regimes of scattering by small bodies with impedance boundary conditions

The paper concerns scattering of plane waves by a bounded obstacle with complex valued impedance boundary conditions. We study the spectrum of the Neumann-to-Dirichlet operator for small wave numbers and long wave asymptotic behavior of the solutions of the scattering problem. The study includes the case when $k=0$ is an eigenvalue or a resonance. The transformation from the impedance to the Dirichlet boundary condition as impedance grows is described. A relation between poles and zeroes of the scattering matrix in the non-self adjoint case is established. The results are applied to a problem of scattering by an obstacle with a springy coating. The paper describes the dependence of the impedance on the properties of the material, that is on forces due to the deviation of the boundary of the obstacle from the equilibrium position

Amplification of simian retroviral sequences from human recipients of baboon liver transplants

Investigations into the use of baboons as organ donors for human transplant recipients, a procedure called xenotransplantation, have raised the specter of transmitting baboon viruses to humans and possibly establishing new human infectious diseases. Retrospective analysis of tissues from two human transplant recipients with end-stage hepatic disease who died 70 and 27 days after the transplantation of baboon livers revealed the presence of two simian retroviruses of baboon origin, simian foamy virus (SFV) and baboon endogenous virus (BaEV), in multiple tissue compartments. The presence of baboon mitochondrial DNA was also detected in these same tissues, suggesting that xenogeneic 'passenger leukocytes' harboring latent or active viral infections had migrated from the xenografts to distant sites within the human recipients. The persistence of SFV and BaEV in human recipients throughout the posttransplant period underscores the potential infectious risks associated with xenotransplantation