949 research outputs found
Inflation Expectations and the Conduct of Monetary Policy: A Review of Recent Evidence and Experience
This article explores the role of inflation expectations in the conduct of monetary policy. It reviews the various measures of inflation expectations used by central banks, including surveys and market-based indicators, and considers their advantages and disadvantages. It examines the critical role of inflation expectations in the framework that central banks use to understand, forecast, and control inflation. It also looks at their role as an indicator of central bank credibility. The behaviour of inflation expectations over the past two years is analyzed and policy conclusions are offered.
Analysis of Hydrogen Cyanide Hyperfine Spectral Components towards Star Forming Cores
Although hydrogen cyanide has become quite a common molecular tracing species
for a variety of astrophysical sources, it, however, exhibits dramatic non-LTE
behaviour in its hyperfine line structure. Individual hyperfine components can
be strongly boosted or suppressed. If these so-called hyperfine line anomalies
are present in the HCN rotational spectra towards low or high mass cores, this
will affect the interpretation of various physical properties such as the line
opacity and excitation temperature in the case of low mass objects and infall
velocities in the case of their higher mass counterparts. This is as a
consequence of the direct effects that anomalies have on the underlying line
shape, be it with the line structural width or through the inferred line
strength. This work involves the first observational investigation of these
anomalies in two HCN rotational transitions, J=1!0 and J=3!2, towards both low
mass starless cores and high mass protostellar objects. The degree of anomaly
in these two rotational transitions is considered by computing the ratios of
neighboring hyperfine lines in individual spectra. Results indicate some degree
of anomaly is present in all cores considered in our survey, the most likely
cause being line overlap effects among hyperfine components in higher
rotational transitions.Comment: 8th Serbian Conference on Spectral Line Shapes in Astrophysics,
Divicibare; 8 pages, 5 figure
Stratosphere-troposphere separation of nitrogen dioxide columns from the TEMPO geostationary satellite instrument
Separating the stratospheric and tropospheric contributions in satellite retrievals of atmospheric NO2 column abundance is a crucial step in the interpretation and application of the satellite observations. A variety of stratosphere–troposphere separation algorithms have been developed for sun-synchronous instruments in low Earth orbit (LEO) that benefit from global coverage, including broad clean regions with negligible tropospheric NO2 compared to stratospheric NO2. These global sun-synchronous algorithms need to be evaluated and refined for forthcoming geostationary instruments focused on continental regions, which lack this global context and require hourly estimates of the stratospheric column. Here we develop and assess a spatial filtering algorithm for the upcoming TEMPO geostationary instrument that will target North America. Developments include using independent satellite observations to identify likely locations of tropospheric enhancements, using independent LEO observations for spatial context, consideration of diurnally varying partial fields of regard, and a filter based on stratospheric to tropospheric air mass factor ratios. We test the algorithm with LEO observations from the OMI instrument with an afternoon overpass, and from the GOME-2 instrument with a morning overpass.
We compare our TEMPO field of regard algorithm against an identical global algorithm to investigate the penalty resulting from the limited spatial coverage in geostationary orbit, and find excellent agreement in the estimated mean daily tropospheric NO2 column densities (R2=0.999, slope=1.009 for July and R2=0.998, slope=0.999 for January). The algorithm performs well even when only small parts of the continent are observed by TEMPO. The algorithm is challenged the most by east coast morning retrievals in the wintertime (e.g., R2=0.995, slope=1.038 at 14:00 UTC). We find independent global LEO observations (corrected for time of day) provide important context near the field-of-regard edges. We also test the performance of the TEMPO algorithm without these supporting global observations. Most of the continent is unaffected (R2=0.924 and slope=0.973 for July and R2=0.996 and slope=1.008 for January), with 90 % of the pixels having differences of less than ±0.2×1015 molecules cm−2 between the TEMPO tropospheric NO2 column density and the global algorithm. For near-real-time retrieval, even a climatological estimate of the stratospheric NO2 surrounding the field of regard would improve this agreement. In general, the additional penalty of a limited field of regard from TEMPO introduces no more error than normally expected in most global stratosphere–troposphere separation algorithms. Overall, we conclude that hourly near-real-time stratosphere–troposphere separation for the retrieval of NO2 tropospheric column densities by the TEMPO geostationary instrument is both feasible and robust, regardless of the diurnally varying limited field of regard.The authors are grateful to Kelly Chance, Xiong Liu, John Houck, Peter Zoogman, and other members of the TEMPO trace gas retrieval team for their input in preparation of this paper. Work at Dalhousie University was supported by Environment and Climate Change Canada. The authors also gratefully acknowledge the free use of TEMIS NO2 data from the GOME-2 sensor provided by http://www.temis.nl, last access: 12 November 2018, and the NASA Standard Product NO2 data from OMI provided by https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary, last access: 9 November 2018. (Environment and Climate Change Canada)https://www.atmos-meas-tech.net/11/6271/2018/Published versio
Protostellar Outflow Evolution in Turbulent Environments
The link between turbulence in star formatting environments and protostellar
jets remains controversial. To explore issues of turbulence and fossil cavities
driven by young stellar outflows we present a series of numerical simulations
tracking the evolution of transient protostellar jets driven into a turbulent
medium. Our simulations show both the effect of turbulence on outflow
structures and, conversely, the effect of outflows on the ambient turbulence.
We demonstrate how turbulence will lead to strong modifications in jet
morphology. More importantly, we demonstrate that individual transient outflows
have the capacity to re-energize decaying turbulence. Our simulations support a
scenario in which the directed energy/momentum associated with cavities is
randomized as the cavities are disrupted by dynamical instabilities seeded by
the ambient turbulence. Consideration of the energy power spectra of the
simulations reveals that the disruption of the cavities powers an energy
cascade consistent with Burgers'-type turbulence and produces a driving
scale-length associated with the cavity propagation length. We conclude that
fossil cavities interacting either with a turbulent medium or with other
cavities have the capacity to sustain or create turbulent flows in star forming
environments. In the last section we contrast our work and its conclusions with
previous studies which claim that jets can not be the source of turbulence.Comment: 24 pages, submitted to the Astrophysical Journa
Towards High-Flux Isolated Attosecond Pulses with a 200 TW CPA
Attosecond pulses have been developed as a means for investigating phenomena that proceed on the order of the atomic unit of time (24 as). Unfortunately, these extreme ultraviolet (XUV) pulses by themselves contain too few photons to initiate nonlinear dynamics or dress states in an attosecond pump--attosecond probe scheme. As a result, most attosecond experiments thus far have featured complementary near infrared (NIR) femtosecond lasers for instigating electron dynamics. In order to access the benefits of all-attosecond measurements and open attosecond physics to new fields of exploration, the photon flux of these pulses must be increased. One way to boost the attosecond pulse energy is to scale up the energy of the NIR pulse responsible for driving high-harmonic generation (HHG). With generalized double optical gating (GDOG), isolated attosecond pulses can be generated with multi-cycle laser systems, wherein the pulse energy can be boosted more easily than in the few-cycle laser systems required by other gating methods. At the Institute for the Frontier of Attosecond Science and Technology (IFAST), this scalability was demonstrated using a 350 mJ, 15 fs (10 TW) Ti:sapphire laser, which was used to generate a 100 nJ XUV continuum. This represented an order-of-magnitude improvement over typical attosecond pulse energies achievable by millijoule-level few-cycle lasers. To obtain the microjoule-level attosecond pulse energy required for performing all-attosecond experiments, the attosecond flux generated by the IFAST 10 TW system was still deficient by an order of magnitude. To this end, the laser system was upgraded to provide joule-level output energies while maintaining pulse compression to 15 fs, with a targeted peak power of 200 TW. This was accomplished by adding an additional Ti:sapphire amplifier to the existing 10 TW system and implementing a new pulse compression system to accommodate the higher pulse energy. Because this system operated at a 10 Hz repetition rate, stabilization of the carrier-envelope phase (CEP) -- important for controlling attosecond pulse production -- could not be achieved using traditional methods. Therefore, a new scheme was developed, demonstrating the first-ever control of CEP in a chirped-pulse amplifier (CPA) at low repetition rates. Finally, a new variation of optical gating was proposed as a way to improve the efficiency of the attosecond pulse generation process. This method was also predicted to allow for the generation of isolated attosecond pulses with longer driving laser pulses, as well as the extension of the high-energy photon cut-off of the XUV continuum
Isotropically Driven versus Outflow Driven Turbulence: Observational Consequences for Molecular Clouds
Feedback from protostellar outflows can influence the nature of turbulence in
star forming regions even if they are not the primary source of velocity
dispersion for all scales of molecular clouds. For the rate and power expected
in star forming regions, we previously (Carroll et al. 2009) demonstrated that
outflows could drive supersonic turbulence at levels consistent with the
scaling relations from Matzner 2007 although with a steeper velocity power
spectrum than expected for an isotropically driven supersonic turbulent
cascade. Here we perform higher resolution simulations and combine simulations
of outflow driven turbulence with those of isotropically forced turbulence. We
find that the presence of outflows within an ambient isotropically driven
turbulent environment produces a knee in the velocity power spectrum at the
outflow scale and a steeper slope at sub-outflow scales than for a purely
isotropically forced case. We also find that the presence of outflows flattens
the density spectrum at large scales effectively reducing the formation of
large scale turbulent density structures. These effects are qualitatively
independent of resolution. We have also carried out Principal Component
Analysis (PCA) for synthetic data from our simulations. We find that PCA as a
tool for identifying the driving scale of turbulence has a misleading bias
toward low amplitude large scale velocity structures even when they are not
necessarily the dominant energy containing scales. This bias is absent for
isotropically forced turbulence but manifests strongly for collimated outflow
driven turbulence.Comment: 30 pages, 10 figures, Submitted to Ap
Management of RFID Systems in Hospital Transfusion Services
Radio Frequency Identification Devices (RFID) technology is used by hospital supply chains to track various medical products and monitor inventories. To improve overall operations, hospitals have implemented RFID as part of their supply chain processes. Hospitals have also have begun incorporating RFID technology as part of their transfusion services processes. The purpose of this review was to analyze how healthcare organization supply chains can benefit from the utilization of RFID systems in transfusion services departments. The methodology for this study was a literature review following the steps of a systematic review with a total of 51 sources referenced.
RFID technology is being used to manage and track blood products from the initial donor phlebotomy to final disposition or product transfusion. Through RFID, transfusion departments and hospital supply chains have been able to manage blood samples and components to facilitate identification and transfusion of blood products to the correct patient. RFID-enabled transfusion practices have successfully increased provider productivity and product quality through work-reduction times and error reduction. A pilot study in one Iowa hospital system yielded a 3%-10% reduction in misidentification of patients and/or blood products during transfusion. A cost-benefit assessment reported showed a 5-year ROI of 2%, with an approximate pay-back period of four years. Cost of RFID tags can be 10-15 times more expensive than barcode systems. There are also risks of this technology involving privacy and the security of patient information.
Findings of this research study suggest that RFID has provided improvements in quality of care and efficiency, while initial costs, security and privacy appeared as principal barriers of adoption
Benefits and Barriers of Implementation and Utilization of Radio-Frequency Identification (RFID) Systems in Transfusion Medicine
Radio-frequency identification (RFID) technology is used by hospital supply chains to track medical products and monitor inventories. Hospitals have also begun incorporating RFID technology as part of their transfusion processes. The purpose of this review was to analyze how healthcare organization supply chains can benefit from the utilization of RFID systems in transfusion service departments. The methodology for this study was a literature review following the steps of a systematic review with a total of 52 sources referenced. RFID technology is used to manage and track blood products from the initial donor phlebotomy to final disposition or product transfusion. RFID-enabled transfusion practices have successfully increased provider productivity and product quality through work-time reduction and error reduction. Findings of this research study suggest that RFID has provided improvements in quality of care and efficiency, while initial costs, security, and privacy appear to be the principal barriers to adoption
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