12,406 research outputs found
Performance of Hybrid NbTiN-Al Microwave Kinetic Inductance Detectors as Direct Detectors for Sub-millimeter Astronomy
In the next decades millimeter and sub-mm astronomy requires large format
imaging arrays and broad-band spectrometers to complement the high spatial and
spectral resolution of the Atacama Large Millimeter/sub-millimeter Array. The
desired sensors for these instruments should have a background limited
sensitivity and a high optical efficiency and enable arrays thousands of pixels
in size. Hybrid microwave kinetic inductance detectors consisting of NbTiN and
Al have shown to satisfy these requirements. We present the second generation
hybrid NbTiN-Al MKIDs, which are photon noise limited in both phase and
amplitude readout for loading levels fW. Thanks to the
increased responsivity, the photon noise level achieved in phase allows us to
simultaneously read out approximately 8000 pixels using state-of-the-art
electronics. In addition, the choice of superconducting materials and the use
of a Si lens in combination with a planar antenna gives these resonators the
flexibility to operate within the frequency range THz. Given
these specifications, hybrid NbTiN-Al MKIDs will enable astronomically usable
kilopixel arrays for sub-mm imaging and moderate resolution spectroscopy.Comment: 7 pages, 3 figures. Presented at SPIE Astronomical Telescopes and
Instrumentation 2014: Millimeter, Submillimeter, and Far-Infrared Detectors
and Instrumentation for Astronomy VI
Photon noise limited radiation detection with lens-antenna coupled Microwave Kinetic Inductance Detectors
Microwave Kinetic Inductance Detectors (MKIDs) have shown great potential for
sub-mm instrumentation because of the high scalability of the technology. Here
we demonstrate for the first time in the sub-mm band (0.1...2 mm) a photon
noise limited performance of a small antenna coupled MKID detector array and we
describe the relation between photon noise and MKID intrinsic
generation-recombination noise. Additionally we use the observed photon noise
to measure the optical efficiency of detectors to be 0.8+-0.2.Comment: The following article has been submitted to AP
Interactive Effects of Inducible Defense and Resource Availability on Phlorotannins in the North Atlantic Brown Alga \u3ci\u3eFucus vesiculosus\u3c/i\u3e
Research seeking to explain the ecological role of polyphenolics (phlorotannins) in plants and brown algae has largely focused on 2 alternative concepts, the carbon/nutrient (C/N) balance and the inducible defense models. We tested the hierarchy of effects of both models on phlorotannin production in the brown alga Fucus vesiculosus (Fucales) by simultaneously manipulating the N environment and simulating herbivory for 2 oceanic (high and low intertidal) and estuarine populations. We measured phlorotannin levels in algae under control, grazed, N-enriched, and grazed + N-enriched treatments with time (0 to 14 d) throughout the year to determine onset and duration of the response. We found greater support for the inducible defense model; generally, both grazed and grazed + N- enriched fronds had significantly higher phlorotannin concentrations than control thalli. When we found an inducible response, it was rapid (within 3 d) and relatively long term (\u3e2 wk). However, the induced response was minimal for both oceanic populations during March, perhaps due to fixed-C limitation, and was absent for the estuarine and high intertidal populations during June, the period of peak phlorotannins at both sites. Although N enrichment resulted in depressed concentrations of phlorotannins only for the estuarine population, we did measure a significant negative correlation between tissue N and phenolics for the oceanic population, as predicted by the C/N balance model. Thus, while the inducible defense response takes preeminence over resource availability effects (C/N balance hypothesis), this study revealed that phlorotannin production is likely controlled by a complex interaction of environmental, developmental and defense-related factors, emphasizing the applicability of both models in marine systems
Integrated Filterbank for DESHIMA: A Submillimeter Imaging Spectrograph Based on Superconducting Resonators
An integrated filterbank (IFB) in combination with microwave kinetic
inductance detectors (MKIDs), both based on superconducting resonators, could
be used to make broadband submillimeter imaging spectrographs that are compact
and flexible. In order to investigate the possibility of adopting an IFB
configuration for DESHIMA (Delft SRON High-redshift Mapper), we study the basic
properties of a coplanar-waveguide-based IFB using electromagnetic simulation.
We show that a coupling efficiency greater than 1/2 can be achieved if
transmission losses are negligible. We arrive at a practical design for a 9
pixel x 920 color 3 dimensional imaging device that fits on a 4 inch wafer,
which instantaneously covers multiple submillimeter telluric windows with a
dispersion of f/df = 1000.Comment: 6 pages, 4 figures, submitted to LTD-14 / Journal of Low Temperature
Physic
First Detection of Millimeter/Submillimeter Extragalactic H2O Maser Emission
We report the first detection of an extragalactic millimeter wavelength H2O
maser at 183 GHz towards NGC 3079 using the Submillimeter Array (SMA), and a
tentative submillimeter wave detection of the 439 GHz maser towards the same
source using the James Clerk Maxwell Telescope (JCMT). These H2O transitions
are known to exhibit maser emission in star-forming regions and evolved stars.
NGC 3079 is a well-studied nuclear H2O maser source at 22 GHz with a
time-variable peak flux density in the range 3 -- 12 Jy. The 183 GHz H2O maser
emission, with peak flux density 0.5 Jy (7 detection), also
originates from the nuclear region of NGC 3079 and is spatially coincident with
the dust continuum peak at 193 GHz (53 mJy integrated). Peak emission at both
183 and 439 GHz occurs in the same range of velocity as that covered by the 22
GHz spectrum. We estimate the gas to dust ratio of the nucleus of NGC 3079 to
be 150, comparable to the Galactic value of 160. Discovery of maser
emission in an active galactic nucleus beyond the long-known 22 GHz transition
opens the possibility of future position-resolved radiative transfer modeling
of accretion disks and outflows pc from massive black holes.Comment: 12 pages, 3 figures, ApJ Letters accepte
Evidence for Nodal superconductivity in SrScFePO
Point contact Andreev reflection spectra have been taken as a function of
temperature and magnetic field on the polycrystalline form of the newly
discovered iron-based superconductor Sr2ScFePO3. A zero bias conductance peak
which disappears at the superconducting transition temperature, dominates all
of the spectra. Data taken in high magnetic fields show that this feature
survives until 7T at 2K and a flattening of the feature is observed in some
contacts. Here we inspect whether these observations can be interpreted within
a d-wave, or nodal order parameter framework which would be consistent with the
recent theoretical model where the height of the P in the Fe-P-Fe plane is key
to the symmetry of the superconductivity. However, in polycrystalline samples
care must be taken when examining Andreev spectra to eliminate or take into
account artefacts associated with the possible effects of Josephson junctions
and random alignment of grains.Comment: Published versio
'Grey nomad' travellers' use of remote health services in Australia: a qualitative enquiry of hospital managers' perspectives.
BACKGROUND: For more than the last two decades, older Australians travelling domestically in self-sufficient accommodation and recreational vehicles for extended periods of time have been referred to as 'Grey Nomads'. By 2021 more than 750,000 such recreational vehicles were registered in Australia. Tourism data for the year to September 2017 show 11.8 million domestic camping and caravanning trips in Australia, 29% of which were people aged 55 and over. As the 'baby boomer' generation increasingly comes to retirement, the size of this travelling population is growing. This term applies to the spike in birth rates after World War II from 1946-1964. This growing group of domestic travellers are potential healthcare consumers in remote areas but relatively little is known about their travel, healthcare needs or care seeking practices. Grey nomads have been described as reflective of the age-comparable sector of the Australian population in that many live with chronic illness. Early concerns were raised that they may "burden" already stretched rural and remote healthcare services but relatively little is known about the impact of these travellers. METHODS: The aim of this study was to explore the utilisation of healthcare services in remote locations in Australia by grey nomads including women travellers, from the perspective of healthcare professionals working in these settings. The study objective was to interview healthcare professionals to seek their experience and details of service delivery to grey nomads. In March 2020 [prior to state border closures due to the COVID-19 pandemic] a field study was conducted to identify the impact of grey nomads on healthcare services in remote New South Wales and Queensland. A qualitative approach was taken to explore the perspectives of nursing healthcare managers working in remote towns along a popular travel route. With appropriate Research Ethics Committee approval, managers were purposively sampled and sample size was determined by data saturation. Thirteen managers were contacted and twelve interviews were scheduled to take place face to face in the healthcare facilities (small hospitals with acute care and aged care services) at mutually convenient times. A semi-structured interview schedule was developed in line with the research aim. The interviews were audio-recorded, transcribed and thematic analysis was undertaken concurrently with data collection for ongoing refinement of questions and to address emerging issues. RESULTS: These nursing managers described a strong service and community ethos. They regarded travellers' healthcare needs no differently to those of local people and described their strong commitment to the provision of healthcare services for their local communities, applying an inclusive definition of community. Traveller presentations were described as predominantly exacerbations of chronic illness such as chest pain, medication-related attendances, and accidents and injuries. No hospital activity data for traveller presentations were available as no reports were routinely generated. Travellers were reported as not always having realistic expectations about what healthcare is available in remote areas and arriving with mixed levels of preparedness. Most travellers were said to be well-prepared for their travel and self-management of their health. However, the healthcare services that can be provided in rural and remote areas needed to be better understood by travellers from metropolitan areas and their urban healthcare providers. CONCLUSION: Participants did not perceive travellers as a burden on health services but recommendations were made regarding their expectations and preparedness. Australia's national transition to electronic health records including a patient-held record was identified as a future support for continuity of care for travellers and to facilitate treatment planning. With no current information to characterise traveller presentations, routinely collected hospital data could be extracted to characterise this patient population, their presentations and the resources required to meet their care needs
Simulation studies of improved sounding systems
Two instrument designs for indirect satellite sounding of the atmosphere in the infrared are represented by the High Resolution Infra-Red Sounder, Model 2 (HIRS-2) and by the Advanced Meteorological Temperature Sounder (AMTS). The relative capabilities of the two instruments were tested by simulating satellite measurements from a group of temperature soundings, allowing the two participants to retrieve the temperature profiles from the simulated data, and comparing the results with the original temperature profiles. Four data sets were produced from radiosondes data extrapolated to a suitable altitude, representing continents and oceans, between 30S and 30N. From the information available, temperature profiles were retrieved by two different methods, statistical regression and inversion of the radiative transfer equation. Results show the consequence of greater spectral purity, concomitant increase in the number of spectral intervals, and the better spatial resolution in partly clouded areas. At the same time, the limitation of the HIRS-2 without its companion instrument leads to some results which should be ignored in comparing the two instruments. A clear superiority of AMTS results is shown
Testing the clump model of SiO maser emission
Building on the detection of J=7-6 SiO maser emission in both the v=1 and v=2
vibrational states towards the symbiotic Mira, R Aquarii, we have used the
James Clerk Maxwell Telescope to study the changes in the SiO maser features
from R Aqr over a stellar pulsational period. The observations, complemented by
contemporaneous data taken at 86 GHz, represent a test of the popular
thermal-instability clump models of SiO masers. The `clump' model of SiO maser
emission considers the SiO masers to be discrete emitting regions which differ
from their surroundings in the values of one or more physical variables (SiO
abundance, for example). We find that our observational data are consistent
with a clump model in which the appearance of maser emission in the J=7-6
transitions coincides with an outward-moving shock impinging on the inner edge
of the maser zone.Comment: 7 pages, 2 figures, accepted for MNRA
Sports medicine in Hawaii: care of the high school athlete in Oahu's public schools.
A recent study by the National Athletic Trainers Association indicated that injuries occur more often during practice than during games in high school athletics. Results of the 3-year study indicated that 60% of basketball injuries occurred in boys and young men during practice and 59% occurred in women. About 2/3 of the estimated 120,000 injuries suffered by prep wrestlers each year happen during practice. The study found that an average of 331,865 high school football players (1/3 of the million who play football each year) were sidelined by an injury at least once. With these statistics in mind, our study looks at the approach to the management of injury in the public schools that make up the Oahu Inter-scholastic Association (OIA) in the state of Hawaii. The estimated number of student athletes that participate in organized athletics in the OIA is 7,960 and the number of coaches is 1,189
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