2,489 research outputs found
Education and the World's Most Rapid Fertility Decline in Iran
A first analysis of the Iran 2006 census results shows a sensationally low fertility level of 1.9 for the whole country and only 1.5 for the Tehran area (which has about 8 million people). The lowest total fertility rate of 1.3 was recorded for Gilan and Mazandaran provinces. In a recent study, Abbasi-Shavazi and McDonald (2006) emphasized the likely role of greatly improved female education in this trend. However, this hypothesis has not been thoroughly tested and they have not yet provided any formal analysis on this important factor. In the conclusions they express the expectation that fertility in Iran would continue to fall well below replacement level. This paper follows up on the Abbasi-Shavazi and McDonald (2006) paper in two important ways: 1) It presents fertility estimates based on the 2006 census which indicate a substantial further fertility decline; and 2) it presents reconstructions (back to 1970) and projections (to 2030) of the population of Iran by age, sex and level of educational attainment. It decomposes quantitatively to what extent this precipitous fertility decline can be attributed to the rapidly increasing educational attainment of women, and draws more general conclusions for theories of fertility decline
Cosmic Rays at the Highest Energies -- First Data from the Pierre Auger Observatory --
The southern Pierre Auger Observatory, presently under construction in
Malarg"ue, Argentina, is nearing completion. The instrument is designed to
measure extensive air-showers with energies ranging from - eV
and beyond. It combines two complementary observation techniques; the detection
of particles at ground and the coincident observation of associated
fluorescence light generated in the atmosphere above the ground. This is being
realized by employing an array of 1600 water Cherenkov detectors, distributed
over an area of 3000 km, and operating 24 wide-angle Schmidt telescopes,
positioned at four sites at the border of the ground array. The Observatory
will reach its full size only in 2007 but data are routinely recorded already
and have started to provide relevant science results. This talk will focus on
the detector characterizations and presents first results on the arrival
direction of extremely-high energy cosmic rays, their energy spectrum, and on
the upper limit of the photon fraction.Comment: Invited paper presented at the International Symposium on Heavy Ion
Physics 2006 (ISHIP 2006), Heavy Ion Physics - Gateway to the Unknown:
Complex Structures in Elementary Matter, April 3-6, 2006 Frankfurt am Main,
Germany; 13 pages, 7 figure
The MIDAS experiment: A prototype for the microwave emission of Ultra-High Energy Cosmic Rays
Recent measurements suggest that extensive air showers initiated by
ultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the
electromagnetic spectrum caused by the collisions of the free-electrons with
the atmospheric neutral molecules in the plasma produced by the passage of the
shower. Such emission is isotropic and could allow the detection of air showers
with 100% duty cycle and a calorimetric-like energy measurement, a significant
improvement over current detection techniques. We have built MIDAS (MIcrowave
Detection of Air Showers), a prototype of microwave detector, which consists of
a 4.5 m diameter antenna with a cluster of 53 feed-horns in the 4 GHz range.
The details of the prototype and first results will be presented.Comment: To appear in the proceedings of 12th Topical Seminar on Innovative
Particle and Radiation Detectors (IPRD10), Siena, Italy, 7 - 10 June 201
The effect of staining and bleaching on the color of two different types of composite restoration
Long term success of composite restorations depends greatly on their color stability and esthetic appearance. This study aimed to assess the effects of commonly consumed beverage and bleaching on the color of composite restoration. Two resin composite
The primary structure of three hemoglobin chains from the indigo snake (Drymarchon corais erebennus, Serpentes): First evidence for αD chains and two β chain types in snakes
The hemoglobin of the indigo snake (Drymarchon corais erebennus, Colubrinae) consists of two components, HbA and HbD, in the ratio of 1:1. They differ in both their alpha and beta chains. The amino acid sequences of both alpha chains (alpha(A) and alpha(D)) and one beta chain (betaI) were determined. The presence of an alpha(D)chain in a snake hemoglobin is described for the first time. A comparison of all snake beta chain sequences revealed the existence of two paralogous beta chain types in snakes as well, which are designated as betaI and betaII type. For the discussion of the physiological properties of Drymarchon hemoglobin, the sequences were compared with those of the human alpha and beta chains and those of the closely related water snake Liophis miliaris where functional data are available. Among the heme contacts, the substitution alpha(D)58(E7)His-->Gln is unusual but most likely without any effect. The residues responsible for the main part of the Bohr effect are the same as in mammalian hemoglobins. In each of the three globin chains only two residues at positions involved in the alpha1/beta2 interface contacts, most important for the stability and the properties of the hemoglobin molecule, are substituted with regard to human hemoglobin. On the contrary, nine, eleven, and six alpha1/beta1 contact residues are replaced in the alpha(A), alpha(D), betaI chains, respectively
Report of the Working Group on the Composition of Ultra High Energy Cosmic Rays
For the first time a proper comparison of the average depth of shower maximum
() published by the Pierre Auger and Telescope Array Observatories
is presented. The distributions measured by the Pierre Auger
Observatory were fit using simulated events initiated by four primaries
(proton, helium, nitrogen and iron). The primary abundances which best describe
the Auger data were simulated through the Telescope Array (TA) Middle Drum (MD)
fluorescence and surface detector array. The simulated events were analyzed by
the TA Collaboration using the same procedure as applied to their data. The
result is a simulated version of the Auger data as it would be observed by TA.
This analysis allows a direct comparison of the evolution of with energy of both data sets. The
measured by TA-MD is consistent with a preliminary simulation of the Auger data
through the TA detector and the average difference between the two data sets
was found to be .Comment: To appear in the Proceedings of the UHECR workshop, Springdale USA,
201
Adaptive Input Shaper for Payload Swing Control of a 5-DOF Tower Crane with Parameter Uncertainties and Obstacle Avoidance
Highest Energy Cosmic Rays and results from the HiRes Experiment
The status of the field of ultrahigh energy cosmic rays is summarized, from
the point of view of the latest results of the High Resolution Fly's Eye
(HiRes) Experiment. HiRes results are presented, and compared with those of the
Akeno Giant Air Shower Array (AGASA), plus the Telescope Array and Pierre Auger
experiments. The HiRes measurements of the cosmic ray spectrum, and the
observation of the GZK cutoff are presented. HiRes results on composition,
searches for anisotropy, measurement of the proton-air total cross section, and
shapes of shower profiles are presented.Comment: 31 pages, 18 figures, submitted to Journal of Physics
TailX: Scheduling Heterogeneous Multiget Queries to Improve Tail Latencies in Key-Value Stores
International audienceUsers of interactive services such as e-commerce platforms have high expectations for the performance and responsiveness of these services. Tail latency, denoting the worst service times, contributes greatly to user dissatisfaction and should be minimized. Maintaining low tail latency for interactive services is challenging because a request is not complete until all its operations are completed. The challenge is to identify bottleneck operations and schedule them on uncoordinated backend servers with minimal overhead, when the duration of these operations are heterogeneous and unpredictable. In this paper, we focus on improving the latency of multiget operations in cloud data stores. We present TailX, a task-aware multiget scheduling algorithm that improves tail latencies under heterogeneous workloads. TailX schedules operations according to an estimation of the size of the corresponding data, and allows itself to procrastinate some operations to give way to higher priority ones. We implement TailX in Cassandra, a widely used key-value store. The result is an improved overall performance of the cloud data stores for a wide variety of heterogeneous workloads. Specifically, our experiments under heterogeneous YCSB workloads show that TailX outperforms state-of-the-art solutions and reduces tail latencies by up to 70% and median latencies by up to 75%
Error estimation in reduced basis method for systems with time-varying and nonlinear boundary conditions
Many physical phenomena, such as mass transport and heat transfer, are modeled by systems of partial differential equations with time-varying and nonlinear boundary conditions. Control inputs and disturbances typically affect the system dynamics at the boundaries and a correct numerical implementation of boundary conditions is therefore crucial. However, numerical simulations of high-order discretized partial differential equations are often too computationally expensive for real-time and many-query analysis. For this reason, model complexity reduction is essential. In this paper, it is shown that the classical reduced basis method is unable to incorporate time-varying and nonlinear boundary conditions. To address this issue, it is shown that, by using a modified surrogate formulation of the reduced basis ansatz combined with a feedback interconnection and a input-related term, the effects of the boundary conditions are accurately described in the reduced-order model. The results are compared with the classical reduced basis method. Unlike the classical method, the modified ansatz incorporates boundary conditions without generating unphysical results at the boundaries. Moreover, a new approximation of the bound and a new estimate for the error induced by model reduction are introduced. The effectiveness of the error measures is studied through simulation case studies and a comparison with existing error bounds and estimates is provided. The proposed approximate error bound gives a finite bound of the actual error, unlike existing error bounds that grow exponentially over time. Finally, the proposed error estimate is more accurate than existing error estimates
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