178 research outputs found
Religion and modernity: Ritual transformations and the reconstruction of space and time
Social and Cultural Geography1129-4
Scaling up MIMO: Opportunities and Challenges with Very Large Arrays
This paper surveys recent advances in the area of very large MIMO systems.
With very large MIMO, we think of systems that use antenna arrays with an
order of magnitude more elements than in systems being built today, say a
hundred antennas or more. Very large MIMO entails an unprecedented number of
antennas simultaneously serving a much smaller number of terminals. The
disparity in number emerges as a desirable operating condition and a practical
one as well. The number of terminals that can be simultaneously served is
limited, not by the number of antennas, but rather by our inability to acquire
channel-state information for an unlimited number of terminals. Larger numbers
of terminals can always be accommodated by combining very large MIMO technology
with conventional time- and frequency-division multiplexing via OFDM. Very
large MIMO arrays is a new research field both in communication theory,
propagation, and electronics and represents a paradigm shift in the way of
thinking both with regards to theory, systems and implementation. The ultimate
vision of very large MIMO systems is that the antenna array would consist of
small active antenna units, plugged into an (optical) fieldbus.Comment: Accepted for publication in the IEEE Signal Processing Magazine,
October 201
A Tobit Analysis of the Determinants and Potentials of Savings in the Case of Payatas Households
This case study aims to identify the factors affecting household savings in the Area B of Payatas, Quezon City. Particularly, the variables included in the analysis are economic expectations, homeownership, household consumption, household debt, household disposable income, and number of dependents in the household. This paper also aims to analyze the saving potentials of households in Payatas. A total of 422 conditionally and randomly selected households were interviewed through a guided survey questionnaire. The researchers utilized Tobit regression and computed for the conditional marginal effects for both the censored and truncated sample. The results of the study were divided into three: Tobit regression results, conditional marginal effects results on all respondents, and the conditional marginal effects results on household savers. Significant variables such as economic expectations and household disposable income were found to be positively related to household savings, and household consumption was negatively related to household savings. This case study shows that Payatas B households do have saving potentials irrespective of their low income showing high request for accessibility on formal saving institutions
Service availability and readiness for hip fracture care in low- and middle-income countries in South and Southeast Asia
Aims: The aim of this study was to describe the current pathways of care for patients with a fracture of the hip in five low- and middle-income countries (LMIC) in South Asia (Nepal and Sri Lanka) and Southeast Asia (Malaysia, Thailand, and the Philippines).
Methods: The World Health Organization Service Availability and Readiness Assessment tool was used to collect data on the care of hip fractures in Malaysia, Thailand, the Philippines, Sri Lanka, and Nepal. Respondents were asked to provide details about the current pathway of care for patients with hip fracture, including pre-hospital transport, time to admission, time to surgery, and time to weightbearing, along with healthcare professionals involved at different stages of care, information on discharge, and patient follow-up.
Results: Responses were received from 98 representative hospitals across the five countries. Most hospitals were publicly funded. There was consistency in clinical pathways of care within country, but considerable variation between countries. Patients mostly travel to hospital via ambulance (both publicly- and privately-funded) or private transport, with only half arriving at hospital within 12 hours of their injury. Access to surgery was variable and time to surgery ranged between one day and more than five days. The majority of hospitals mobilized patients on the first or second day after surgery, but there was notable variation in postoperative weightbearing protocols. Senior medical input was variable and specialist orthogeriatric expertise was unavailable in most hospitals.
Conclusion: This study provides the first step in mapping care pathways for patients with hip fracture in LMIC in South Asia. The previous lack of data in these countries hampers efforts to identify quality standards (key performance indicators) that are relevant to each different healthcare system
Dynamic baroreflex control of blood pressure: influence of the heart vs. peripheral resistance
The aim in the present experiments was to assess the dynamic baroreflex control of blood pressure, to develop an accurate mathematical model that represented this relationship, and to assess the role of dynamic changes in heart rate and stroke volume in giving rise to components of this response. Patterned electrical stimulation [pseudo-random binary sequence (PRBS)] was applied to the aortic depressor nerve (ADN) to produce changes in blood pressure under open-loop conditions in anesthetized rabbits. The stimulus provided constant power over the frequency range 0–0.5 Hz and revealed that the composite systems represented by the central nervous system, sympathetic activity, and vascular resistance responded as a second-order low-pass filter (corner frequency ≈0.047 Hz) with a time delay (1.01 s). The gain between ADN and mean arterial pressure was reasonably constant before the corner frequency and then decreased with increasing frequency of stimulus. Although the heart rate was altered in response to the PRBS stimuli, we found that removal of the heart's ability to contribute to blood pressure variability by vagotomy and β1-receptor blockade did not significantly alter the frequency response. We conclude that the contribution of the heart to the dynamic regulation of blood pressure is negligible in the rabbit. The consequences of this finding are examined with respect to low-frequency oscillations in blood pressure
Magnetic field stabilization for high-accuracy mass measurements on exotic nuclides
The magnetic-field stability of a mass spectrometer plays a crucial role in
precision mass measurements. In the case of mass determination of short-lived
nuclides with a Penning trap, major causes of instabilities are temperature
fluctuations in the vicinity of the trap and pressure fluctuations in the
liquid helium cryostat of the superconducting magnet. Thus systems for the
temperature and pressure stabilization of the Penning trap mass spectrometer
ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the
fluctuations by at least one order of magnitude downto dT=+/-5mK and
dp=+/-50mtorr has been achieved, which corresponds to a relative frequency
change of 2.7x10^{-9} and 1.5x10^{-10}, respectively. With this stabilization
the frequency determination with the Penning trap only shows a linear temporal
drift over several hours on the 10 ppb level due to the finite resistance of
the superconducting magnet coils.Comment: 23 pages, 13 figure
Boojums and the Shapes of Domains in Monolayer Films
Domains in Langmuir monolayers support a texture that is the two-dimensional
version of the feature known as a boojum. Such a texture has a quantifiable
effect on the shape of the domain with which it is associated. The most
noticeable consequence is a cusp-like feature on the domain boundary. We report
the results of an experimental and theoretical investigation of the shape of a
domain in a Langmuir monolayer. A further aspect of the investigation is the
study of the shape of a ``bubble'' of gas-like phase in such a monolayer. This
structure supports a texture having the form of an inverse boojum. The
distortion of a bubble resulting from this texture is also studied. The
correspondence between theory and experiment, while not perfect, indicates that
a qualitative understanding of the relationship between textures and domain
shapes has been achieved.Comment: replaced with published version, 10 pages, 13 figures include
New WMO certified megaflash lightning extremes for flash distance (768 km) and duration (17.01 seconds) recorded from space
Initial global extremes in lightning duration and horizontal distance were established in 2017 (Lang et al. 2017) by an international panel of atmospheric lightning scientists and engineers assembled by the WMO. The subsequent launch of NOAA’s latest GOES-16/17 satellites with their Geostationary Lightning Mappers (GLMs) enabled extreme lightning to be monitored continuously over the western hemisphere up to 55° latitude for the first time. As a result, the former lightning extremes were more than doubled in 2019 to 709 km for distance and 16.730 s for duration (Peterson et al. 2020). Continued detection and analysis of lightning “megaflashes” (Sequin, 2021) has now revealed two flashes that even exceed those 2019 records. As part of the ongoing work of the WMO in detection and documentation of global weather extremes (e.g., El Fadli et al. 2013; Merlone et al. 2010), an international WMO evaluation committee was created to critically adjudicate these two GLM megaflash cases as new records for extreme lightning.We thank S. A. Rutledge and two other reviewers for their valuable comments. M. J. Peterson was supported by the U.S. Department of Energy through the Los Alamos National Laboratory (LANL) Laboratory Directed Research and Development (LDRD) program under project number 20200529ECR. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract 89233218CNA000001). T. Logan supported by a NOAA Grant NA16OAR4320115 “Lightning Mapper Array Operation in Oklahoma and the Texas Gulf Coast Region to Aid Preparation for the GOES-R GLM.” I. Kolmasova was supported by GACR Grant
20-09671. S. D. Zhang was supported by a NOAA Grant NNH19ZDA001N-ESROGSS. The participation of J. Montanya in this work is supported by research Grant ESP2017-86263-C4-2-R funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe,” by the “European Union”; and Grants PID2019-109269RB-C42 funded by MCIN/AEI/10.13039/501100011033.Peer ReviewedPostprint (author's final draft
Multimorbidity in middle age predicts more subsequent hospital admissions than in older age:A nine-year retrospective cohort study of 121,188 discharged in-patients
- …