64,074 research outputs found
Using performance assessment in secondary school mathematics: an empirical study in a Singapore classroom
No full textThis article reports an exploratory study on using performance assessment in mathematics instruction in a high-performing secondary school in Singapore. An intact mathematics class participated in the study, and received chapter-based performance tasks as intervention during regular mathematics lessons for about one and a half school years. The performance tasks used included authentic and/or open-ended tasks. The students’ academic achievements and attitudes in mathematics were compared with a comparison class that did not receive the intervention. Both quantitative and qualitative data were collected, mainly through questionnaire surveys, performance task tests, conventional school exams, and interviews with students and teachers. The results suggest that the students receiving the intervention performed significantly better than their counterparts in solving conventional exam problems, and in general they also showed more positive changes in attitudes towards mathematics and mathematics learning. The students from the experimental class also expressed positive views about the benefits of using performance tasks in promoting their ability in higher order thinking, though no statistically significant difference was detected between the two classes of students in solving unconventional tasks before and after intervention. Overall, the results appear to support teachers’ using contextualised problems in real life situations and open-ended investigations in students’ learning of mathematic
Measurement of the differential and double-differential Drell-Yan cross sections in proton-proton collisions at root s=7 TeV
No full textMeasurements of the differential and double-differential Drell-Yan cross sections are presented using an integrated luminosity of 4.5 (4.8) fb−1 in the dimuon (dielectron) channel of proton-proton collision data recorded with the CMS detector at the LHC at s√ = 7 TeV. The measured inclusive cross section in the Z-peak region (60–120 GeV) is σ(ℓℓ) = 986.4 ± 0.6 (stat.) ± 5.9 (exp. syst.) ± 21.7 (th. syst.) ± 21.7 (lum.) pb for the combination of the dimuon and dielectron channels. Differential cross sections dσ/dm for the dimuon, dielectron, and combined channels are measured in the mass range 15 to 1500 GeV and corrected to the full phase space. Results are also presented for the measurement of the double-differential cross section d2σ/dm d|y| in the dimuon channel over the mass range 20 to 1500 GeV and absolute dimuon rapidity from 0 to 2.4. These measurements are compared to the predictions of perturbative QCD calculations at next-to-leading and next-to-next-to-leading orders using various sets of parton distribution functions
On some aspects of random walks for modelling mobility in a communication network
No full textBibliography: leaf 16.Grant ONR/N00014-75-C-1183.S. K. Leung-Yan-Cheong, E. R. Barnes
Soil moisture retrieval based on LHCP and RHCP GNSS-R signals
No full textSoil moisture can be retrieved using radar techniques or L-band microwave radiometry. Recently, Global Navigation Satellite System Reflectometry (GNSS-R) techniques have been demonstrated to be useful for many applications as sea-state retrieval and soil moisture retrieval. In this paper, GNSS-R signals reflected from the ground are acquired by means of a commercial receiver. These signals are raw sampled and digitalized, before being processed into Delay Doppler Maps (DDMs) and Delay Waveforms (DWs) with an open loop scheme. In this open loop approach, data are continuously acquired, independently on the tracking status of the receiver. An antenna with two channels, left and right circularly polarized and a low level of cross-polarization is used for the acquisition. The value of the permittivity is computed from the SNR with a standard algorithm based on LH polarized reflected signals, and an improved algorithm based on LH and RH reflected signals in order to keep into account the roughness of the surface. Various in situ measurement campaigns on a terrain with known characteristics are described. The values of the permittivity evaluated from the GNSS-R signals are compared with the results obtained by local measurements based on Time Domain Reflectometry technique (TDR). The measurements were performed with a three-rod sensor and a Tektronix Metallic Cable Tester 1502 instrumen
Why hedge? Extent, nature, and determinants of derivative usage in U.S. municipalities
No full textUsing a hand-collected dataset of over 300 observations of large U.S. cities and counties, this paper investigates the extent, nature and determinants of derivatives usage in the municipal sector.Over half of our sample entities engage in derivative transactions and a vast majority of these transactions are intended to manage interest rate risk. Swaps, by far, are the most popular derivative instrument. In terms of the determinants of derivative usage,we find that the propensity to use derivatives as well as the extent of derivative usage is higher for municipalities that are larger and more financially constrained. We do not find growth to be related to municipal derivative usage. Contrary to suggestions made in the popular press, we fail to find managerial opportunism to be a significant factor in municipal derivative usage. We also find that more sophisticated managers of large municipalities and less sophisticated managers of small municipalities are more likely to engage in derivative transactions.Peer reviewe
A study on the reliability of consecutive k-Out-of-n: G systems based on Copula
No full textThe computation of reliability characteristics of a system that consists of dependent components is sometimes difficult especially when the type of dependence is not known. This article introduces the copula method to calculate the reliability of dependent consecutive k-out-of-n: G systems. The components in these systems are dependent on each other and the dependency may be either linear or nonlinear. The copula is a popular tool for modeling the dependence structure of data. It contains the information about the dependency structure of a vector of random variables and can capture nonlinear dependence. Based on the copula theory, the article analyzes the consecutive k-out-of-n: G systems and gets the reliability indexes. Finally, some numerical examples are presented to illustrate the results obtained in this article.Peer reviewe
Capital asset accounting policies under GASB Statement No. 34: Characteristics, antecedents, and implications
No full textIn this paper, we study the evolution of state and local governments’ capital asset accounting policies from the adoption of GASB Statement No. 34 through the fiscal year ending in 2016. We document substantial cross-sectional and time-series variation in the capitalization thresholds and estimated useful lives pertaining to major classes of capital assets, including buildings, equipment, improvements, and infrastructure assets. Diversity in capital asset accounting policies potentially diminishes the comparability of capital asset accounting information across governments and over time. We also discuss matters related to the implementation and ongoing use of the modified approach for reporting infrastructure assets. Our findings are useful to the GASB as well as to users of government financial reports.Peer reviewe
On the market timing and feedback effect of hedging: evidence from U.S. oil and gas producers
No full textPeer reviewe
Cultural identities as reflected in the literature of the Northern and Southern dynasties period (4th-6th centuries A.D.)
No full textDuring the period of the Northern and Southern dynasties of China identity questions became serious in a society thrown into disorder by political, religious and ethnic problems. This thesis uses three books written in the sixth century to
discuss how educated Chinese faced identity problems and how they dealt with them.
The Buddhist monk Huijiao, dealt with the problems of sinifying a foreign religion. He constructed many different identities in addition to the Buddhist one for the monks in his book Gaoseng zhuan, (Lives of Eminent Monks), a collection of biographies of Buddhist monks, to bring Buddhism closer to Chinese tradition and more acceptable by Confucian standards. Through the identity construction he
also made responses to anti-Buddhist ideas.
Yang Xuanzhi's Luoyang qielan ji, (Record of the Monasteries of Luoyang), deals with the identity problems of Chinese officials serving a Xianbei regime in
the north and of the short-lived capital of the Northern Wei in Luoyang. Yang reconstructed a Chinese identity for the lost capital as a true heir of Chinese tradition, as were the emperors, princes and officials who lived there. He created an identity defined not by ethnicity but by culture.
Yan Zhitui's Tanshi jiaxun, (Family Instruction of the Yan Clan), is a book which tells his descendants how to construct and maintain the future identity of his
own family. He drew on his own experience of recovering from repeated political catastrophes to set out an identity that would help the family to survive disordered times and maintain their status in society
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