Status of SuperSpec: A Broadband, On-Chip Millimeter-Wave Spectrometer

SuperSpec is a novel on-chip spectrometer we are developing for multi-object, moderate resolution (R = 100 - 500), large bandwidth (~1.65:1) submillimeter and millimeter survey spectroscopy of high-redshift galaxies. The spectrometer employs a filter bank architecture, and consists of a series of half-wave resonators formed by lithographically-patterned superconducting transmission lines. The signal power admitted by each resonator is detected by a lumped element titanium nitride (TiN) kinetic inductance detector (KID) operating at 100-200 MHz. We have tested a new prototype device that is more sensitive than previous devices, and easier to fabricate. We present a characterization of a representative R=282 channel at f = 236 GHz, including measurements of the spectrometer detection efficiency, the detector responsivity over a large range of optical loading, and the full system optical efficiency. We outline future improvements to the current system that we expect will enable construction of a photon-noise-limited R=100 filter bank, appropriate for a line intensity mapping experiment targeting the [CII] 158 micron transition during the Epoch of ReionizationComment: 16 pages, 10 figures, Proceedings of the SPIE Astronomical Telescopes + Instrumentation 2014 Conference, Vol 9153, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI

NIKA: A millimeter-wave kinetic inductance camera

Current generation millimeter wavelength detectors suffer from scaling limits imposed by complex cryogenic readout electronics. To circumvent this it is imperative to investigate technologies that intrinsically incorporate strong multiplexing. One possible solution is the kinetic inductance detector (KID). In order to assess the potential of this nascent technology, a prototype instrument optimized for the 2 mm atmospheric window was constructed. Known as the N\'eel IRAM KIDs Array (NIKA), it was recently tested at the Institute for Millimetric Radio Astronomy (IRAM) 30-meter telescope at Pico Veleta, Spain. The measurement resulted in the imaging of a number of sources, including planets, quasars, and galaxies. The images for Mars, radio star MWC349, quasar 3C345, and galaxy M87 are presented. From these results, the optical NEP was calculated to be around $1 \times 10^{-15}$ W$/$Hz$^{1/2}$. A factor of 10 improvement is expected to be readily feasible by improvements in the detector materials and reduction of performance-degrading spurious radiation.Comment: Accepted for publication in Astronomy & Astrophysic

A dual-band millimeter-wave kinetic inductance camera for the IRAM 30-meter telescope

Context. The Neel IRAM KIDs Array (NIKA) is a fully-integrated measurement system based on kinetic inductance detectors (KIDs) currently being developed for millimeter wave astronomy. In a first technical run, NIKA was successfully tested in 2009 at the Institute for Millimetric Radio Astronomy (IRAM) 30-meter telescope at Pico Veleta, Spain. This prototype consisted of a 27-42 pixel camera imaging at 150 GHz. Subsequently, an improved system has been developed and tested in October 2010 at the Pico Veleta telescope. The instrument upgrades included dual-band optics allowing simultaneous imaging at 150 GHz and 220 GHz, faster sampling electronics enabling synchronous measurement of up to 112 pixels per measurement band, improved single-pixel sensitivity, and the fabrication of a sky simulator to replicate conditions present at the telescope. Results. The new dual-band NIKA was successfully tested in October 2010, performing in-line with sky simulator predictions. Initially the sources targeted during the 2009 run were re-imaged, verifying the improved system performance. An optical NEP was then calculated to be around 2 \dot 10-16 W/Hz1/2. This improvement in comparison with the 2009 run verifies that NIKA is approaching the target sensitivity for photon-noise limited ground-based detectors. Taking advantage of the larger arrays and increased sensitivity, a number of scientifically-relevant faint and extended objects were then imaged including the Galactic Center SgrB2(FIR1), the radio galaxy Cygnus A and the NGC1068 Seyfert galaxy. These targets were all observed simultaneously in the 150 GHz and 220 GHz atmospheric windows.Comment: Submitted to ApJ (abstract reduced to fit ApJ standards

The use of NDVI and its Derivatives for Monitoring Lake Victoria’s Water Level and Drought Conditions

Normalized Difference Vegetation Index (NDVI), which is a measure of vegetation vigour, and lake water levels respond variably to precipitation and its deficiency. For a given lake catchment, NDVI may have the ability to depict localized natural variability in water levels in response to weather patterns. This information may be used to decipher natural from unnatural variations of a given lake’s surface. This study evaluates the potential of using NDVI and its associated derivatives (VCI (vegetation condition index), SVI (standardised vegetation index), AINDVI (annually integrated NDVI), green vegetation function (F g ), and NDVIA (NDVI anomaly)) to depict Lake Victoria’s water levels. Thirty years of monthly mean water levels and a portion of the Global Inventory Modelling and Mapping Studies (GIMMS) AVHRR (Advanced Very High Resolution Radiometer) NDVI datasets were used. Their aggregate data structures and temporal co-variabilities were analysed using GIS/spatial analysis tools. Locally, NDVI was found to be more sensitive to drought (i.e., responded more strongly to reduced precipitation) than to water levels. It showed a good ability to depict water levels one-month in advance, especially in moderate to low precipitation years. SVI and SWL (standardized water levels) used in association with AINDVI and AMWLA (annual mean water levels anomaly) readily identified high precipitation years, which are also when NDVI has a low ability to depict water levels. NDVI also appears to be able to highlight unnatural variations in water levels. We propose an iterative approach for the better use of NDVI, which may be useful in developing an early warning mechanisms for the management of lake Victoria and other Lakes with similar characteristics

The NIKA2 large-field-of-view millimetre continuum camera for the 30 m IRAM telescope

Context. Millimetre-wave continuum astronomy is today an indispensable tool for both general astrophysics studies (e.g. star formation, nearby galaxies) and cosmology (e.g. cosmic microwave background and high-redshift galaxies). General purpose, large-field-of-view instruments are needed to map the sky at intermediate angular scales not accessible by the high-resolution interferometers (e.g. ALMA in Chile, NOEMA in the French Alps) and by the coarse angular resolution space-borne or ground-based surveys (e.g. Planck, ACT, SPT). These instruments have to be installed at the focal plane of the largest single-dish telescopes, which are placed at high altitude on selected dry observing sites. In this context, we have constructed and deployed a three-thousand-pixel dual-band (150 GHz and 260 GHz, respectively 2 mm and 1.15 mm wavelengths) camera to image an instantaneous circular field-of-view of 6.5 arcmin in diameter, and configurable to map the linear polarisation at 260 GHz. Aims. First, we are providing a detailed description of this instrument, named NIKA2 (New IRAM KID Arrays 2), in particular focussing on the cryogenics, optics, focal plane arrays based on Kinetic Inductance Detectors, and the readout electronics. The focal planes and part of the optics are cooled down to the nominal 150 mK operating temperature by means of an adhoc dilution refrigerator. Secondly, we are presenting the performance measured on the sky during the commissioning runs that took place between October 2015 and April 2017 at the 30-m IRAM telescope at Pico Veleta, near Granada (Spain). Methods. We have targeted a number of astronomical sources. Starting from beam-maps on primary and secondary calibrators we have then gone to extended sources and faint objects. Both internal (electronic) and on-the-sky calibrations are applied. The general methods are described in the present paper. Results. NIKA2 has been successfully deployed and commissioned, performing in-line with expectations. In particular, NIKA2 exhibits full width at half maximum angular resolutions of around 11 and 17.5 arcsec at respectively 260 and 150 GHz. The noise equivalent flux densities are, at these two respective frequencies, 33±2 and 8±1 mJy s1/2. A first successful science verification run was achieved in April 2017. The instrument is currently offered to the astronomy community and will remain available for at least the following ten years

Pronuclear injection-based mouse targeted transgenesis for reproducible and highly efficient transgene expression

Mouse transgenesis has proven invaluable for analysis of gene function and generation of human disease models. We describe here the development of a pronuclear injection-based targeted transgenesis (PITT) system, involving site-specific integration in fertilized eggs. The system was applied to two different genomic target loci to generate a series of transgenic lines including fluorescent mice, which reproducibly displayed strong, ubiquitous and stable transgene expression. We also demonstrated that knockdown mice could be readily generated by PITT by taking advantage of the reproducible and highly efficient expression system. The PITT system, which circumvents the problem of unpredictable and unstable transgene expression of conventional random-integration transgenic mice, reduces the time, cost and effort needed to generate transgenic mice, and is potentially applicable to both in vivo ‘gain-of-function’ and ‘loss-of-function’ studies

Vicrostatin – An Anti-Invasive Multi-Integrin Targeting Chimeric Disintegrin with Tumor Anti-Angiogenic and Pro-Apoptotic Activities

Similar to other integrin-targeting strategies, disintegrins have previously shown good efficacy in animal cancer models with favorable pharmacological attributes and translational potential. Nonetheless, these polypeptides are notoriously difficult to produce recombinantly due to their particular structure requiring the correct pairing of multiple disulfide bonds for biological activity. Here, we show that a sequence-engineered disintegrin (called vicrostatin or VCN) can be reliably produced in large scale amounts directly in the oxidative cytoplasm of Origami B E. coli. Through multiple integrin ligation (i.e., αvβ3, αvβ5, and α5β1), VCN targets both endothelial and cancer cells significantly inhibiting their motility through a reconstituted basement membrane. Interestingly, in a manner distinct from other integrin ligands but reminiscent of some ECM-derived endogenous anti-angiogenic fragments previously described in the literature, VCN profoundly disrupts the actin cytoskeleton of endothelial cells (EC) inducing a rapid disassembly of stress fibers and actin reorganization, ultimately interfering with EC's ability to invade and form tubes (tubulogenesis). Moreover, here we show for the first time that the addition of a disintegrin to tubulogenic EC sandwiched in vitro between two Matrigel layers negatively impacts their survival despite the presence of abundant haptotactic cues. A liposomal formulation of VCN (LVCN) was further evaluated in vivo in two animal cancer models with different growth characteristics. Our data demonstrate that LVCN is well tolerated while exerting a significant delay in tumor growth and an increase in the survival of treated animals. These results can be partially explained by potent tumor anti-angiogenic and pro-apoptotic effects induced by LVCN

Astronomy & Astrophysics NIKA: A millimeter-wave kinetic inductance camera

ABSTRACT Context. Current generation millimeter wavelength detectors suffer from scaling limits imposed by complex cryogenic readout electronics. These instruments typically employ multiplexing ratios well below a hundred. To achieve multiplexing ratios greater than a thousand, it is imperative to investigate technologies that intrinsically incorporate strong multiplexing. One possible solution is the kinetic inductance detector (KID). To assess the potential of this nascent technology, a prototype instrument optimized for the 2 mm atmospheric window was constructed. Known as the Néel IRAM KID Array (NIKA), it has recently been tested at the Institute for Millimetric Radio Astronomy (IRAM) 30-m telescope at Pico Veleta, Spain. Aims. There were four principle research objectives: to determine the practicality of developing a giant array instrument based on KIDs, to measure current in-situ pixel sensitivities, to identify limiting noise sources, and to image both calibration and scientificallyrelevant astronomical sources. Methods. The detectors consisted of arrays of high-quality superconducting resonators electromagnetically coupled to a transmission line and operated at ∼100 mK. The impedance of the resonators was modulated by incident radiation; two separate arrays were tested to evaluate the efficiency of two unique optical-coupling strategies. The first array consisted of lumped element kinetic inductance detectors (LEKIDs), which have a fully planar design properly shaped to enable direct absorbtion. The second array consisted of antenna-coupled KIDs with individual sapphire microlenses aligned with planar slot antennas. Both detectors utilized a single transmission line along with suitable room-temperature digital electronics for continuous readout. Results. NIKA was successfully tested in October 2009, performing in line with expectations. The measurement resulted in the imaging of a number of sources, including planets, quasars, and galaxies. The images for Mars, radio star MWC349, quasar 3C345, and galaxy M 87 are presented. From these results, the optical NEP was calculated to be around 1×10 −15 W/Hz 1/2 . A factor of 10 improvement is expected to be readily feasible by improvements in the detector materials and reduction of performance-degrading spurious radiation

Cardiac Performance with Chronic Hypoxia: Mechanisms regulating stroke volume

When humans are exposed to high altitude hypoxia for a sustained period, the cardiac stroke volume is reduced. The changes in cardiac performance seen at high altitude are a result of complex and concomitant changes in preload, afterload and contractility, although the precise mechanisms underpinning the decrease in stroke volume are not known despite being of scientific interest for over fifty years. In this review, we briefly revisit the seminal work performed in the area before focusing on recent developments that have applied mechanistic experimental models and novel imaging technologies to further understand why stroke volume is decreased in chronic hypoxia. First, the review focuses on systolic contractile function before considering the role of diastolic function and ventricular filling