未来的巴基斯坦地质公园——盐岭          下载免费PDF全文

缅恩·哈森·艾哈迈德 《自然科学博物馆研究》2018,(1):36-39

盐岭包括六个峡谷,具有出露充分的地质学和古生物学特征,并且交通便利。这些特点吸引了研究者对这个独特地区的地质时代测定方面的浓厚兴趣,开始对寒武纪三叶虫、二叠纪腕足类、三叠系下统菊石、下第三系大型有孔虫和上第三系及第四纪脊椎动物产生的古地理进行了研究调查。在地质学家眼中,这些盐岭峡谷充满着如此美妙的地质遗址,堪称为世界上独特的野外自然历史博物馆,同时也可能被建设为巴基斯坦的一个地质公园。  相似文献   

Puberty Predicts Approach But Not Avoidance on the Iowa Gambling Task in a Multinational Sample          下载免费PDF全文

Grace Icenogle  Laurence Steinberg  Thomas M. Olino  Elizabeth P. Shulman  Jason Chein  Liane P. Alampay  Suha M. Al‐Hassan  Hanan M. S. Takash  Dario Bacchini  Lei Chang  Nandita Chaudhary  Laura Di Giunta  Kenneth A. Dodge  Kostas A. Fanti  Jennifer E. Lansford  Patrick S. Malone  Paul Oburu  Concetta Pastorelli  Ann T. Skinner  Emma Sorbring  Sombat Tapanya  Liliana M. Uribe Tirado 《Child development》2017,88(5):1598-1614

According to the dual systems model of adolescent risk taking, sensation seeking and impulse control follow different developmental trajectories across adolescence and are governed by two different brain systems. The authors tested whether different underlying processes also drive age differences in reward approach and cost avoidance. Using a modified Iowa Gambling Task in a multinational, cross‐sectional sample of 3,234 adolescents (ages 9–17; M = 12.87, SD = 2.36), pubertal maturation, but not age, predicted reward approach, mediated through higher sensation seeking. In contrast, age, but not pubertal maturation, predicted increased cost avoidance, mediated through greater impulse control. These findings add to evidence that adolescent behavior is best understood as the product of two interacting, but independently developing, brain systems.  相似文献   

MRI and PET images fusion based on human retina model   总被引：1，自引：0，他引：1  

DANESHVAR Sabalan GHASSEMIAN Hassan 《浙江大学学报(A卷英文版)》2007,8(10):1624-1632

The diagnostic potential of brain positron emission tomography (PET) imaging is limited by low spatial resolution. For solving this problem we propose a technique for the fusion of PET and MRI images. This fusion is a trade-off between the spectral information extracted from PET images and the spatial information extracted from high spatial resolution MRI. The proposed method can control this trade-off. To achieve this goal, it is necessary to build a multiscale fusion model, based on the retinal cell photoreceptors model. This paper introduces general prospects of this model, and its application in multispectral medical image fusion. Results showed that the proposed method preserves more spectral features with less spatial distortion. Comparing with hue-intensity-saturation (HIS), discrete wavelet transform (DWT), wavelet-based sharpening and wavelet-à trous transform methods, the best spectral and spatial quality is only achieved simultaneously with the proposed feature-based data fusion method. This method does not require resampling images, which is an advantage over the other methods, and can perform in any aspect ratio between the pixels of MRI and PET images.  相似文献   

Relationship between social capital and lifestyle among older adults     

Shirin Barzanjeh Atri  Mohammad Hassan Sahebi Hagh  Mohammad Asghari Jafarabadi  Aram Feizi 《Educational gerontology》2013,39(9):562-571

ABSTRACT

Objective: This study was designed with the purpose of determining the relationship between social capital and lifestyle and their sub-variables among older adults.

Methods: This is a cross-sectional study using interviews that was conducted in 2017. This study was performed with randomly selected older people over 60 years of age in an urban area of Iran. Data were collected using a questionnaire in 3-month duration. The relationship between the study variables (lifestyle and social capital) was assessed through correlation analysis (in the case of non control of the underlying variables) and general linear modeling (in the case of control of the underlying variables). Data were analyzed using SPSS v.24 software at a 0.05 significant level.

Results: A total of 512 questionnaires were filed out. According to the Pearson correlation test, all social capital variables were associated with lifestyle components. However, in the general linear model test, feeling of trust and safety (p < 0.001), value of life (p = 0.030), and social participation (p = 0.004) had a significant relationship with the lifestyle.

Conclusions: The results indicated that social capital and lifestyle in the older adults were interconnected. Therefore, there is a need to improve social capital factors, especially social participation, feeling of trust and safety, and value of life, which is in-line with the strategies of achieving healthy older population. The results can be used to learn how to increase lifestyle in older adults.  相似文献   

Bottom line: The veteran student in 2010     

Dr. Anthony M. Hassan  Dr. Robert “Jeff” Jackson  Dr. Douglas R. Lindsay  Dr. Damian G. McCabe  Dr. Joseph E. Sanders III 《About Campus》2010,15(2):30-32

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An exact analytical solution for convective heat transfer in rectangular ducts     

Mohammad Mohsen Shahmardan  Mahmood Norouzi  Mohammad Hassan Kayhani  Amin Amiri Delouei 《浙江大学学报(A卷英文版)》2012,13(10):768-781

An exact analytical solution is obtained for convective heat transfer in straight ducts with rectangular cross-sections for the first time. This solution is valid for both H1 and H2 boundary conditions, which are related to fully developed convective heat transfer under constant heat flux at the duct walls. The separation of variables method and various other mathematical techniques are used to find the closed form of the temperature distribution. The local and mean Nusselt numbers are also obtained as functions of the aspect ratio. A new physical constraint is presented to solve the Neumann problem in non-dimensional analysis for the H2 boundary conditions. This is one of the major innovations of the current study. The analytical results indicate a singularity occurs at a critical aspect ratio of 2.4912 when calculating the local and mean Nusselt numbers.  相似文献   

Comparison of sequential and simultaneous design and optimization in low-temperature liquefaction and gas separation processes     

Nassim Tahouni  M. Hassan Panjeshahi  Abtin Ataei 《Journal of The Franklin Institute》2011,348(7):1456-2446

A great deal of attention has been paid to design and optimization of low-temperature liquefaction and gas separation problems over the past years, due to their difficult nature. In this paper, two approaches featuring sequential and simultaneous methods for selection and arrangement of sub-ambient separation systems and their associated refrigeration cycles are compared. The effect of ignoring heat integration within the separation system and between the separation and refrigeration systems is addressed as well as fixing the sequence order of separation. The optimization is carried out using two famous stochastic search methods i.e. Genetic Algorithm (GA) and Simulated Annealing (SA). Three case studies are examined to illustrate the significant differences between optimization results. Also, the design optimality is re-checked with respect to usage of different refrigerants and the resulting structure is verified by application of a comprehensive exergy analysis.  相似文献   

The role of government in developing the biotechnology industry: a South African perspective     

Ramazan Uctu  Hassan Essop 《普罗米修斯》2013,31(1):21-33

Biotechnology has been identified as one of the key sectors for future economic growth in many countries, with South Africa being no exception. Consequently, the South African government introduced the National Biotechnology Strategy (NBS) in 2001 to modernise the government’s biotechnology institutions and to develop the biotechnology industry, given a changing political and technical environment. An important product of the NBS was the establishment of biotechnology regional innovation centres (BRICs) in 2002, which aimed to develop and commercialise the biotechnology industry. The BRICs, however, were effectively replaced by the creation of the Technology Innovation Agency (TIA) in 2008, which also formed part of the 10-year plan of the Department of Science and Technology (DST). The TIA’s aims are to develop South Africa’s ability to convert local research and development (R&D) into commercial products and services. This paper will explore recent changes in the role of the South African government in its attempts to support and develop the biotechnology industry.  相似文献   

Low-cost sensorless control of four-switch, brushless DC motor drive with direct back-EMF detection     

Abolfazl Halvaei Niasar  Abolfazl Vahedi  Hassan Moghbelli 《浙江大学学报(A卷英文版)》2009,10(2):201-208

We propose a position sensorless control scheme for a four-switch, three-phase brushless DC motor drive, based on the zero crossing point detection of phase back-EMF voltages using newly defined error functions （EFs）. The commutation instants are 30° after detected zero crossing points of the EFs. Developed EFs have greater magnitude rather than phase or line voltages so that the sensorless control can work at a lower speed range. Moreover, EFs have smooth transitions around zero voltage level that reduces the commutation errors. EFs are derived from the filtered terminal voltages Vao and Vbo of two low-pass filters, which are used to eliminate high frequency noises for calculation of the average terminal voltages. The feasibility of the proposed sensorless control is demonstrated by simulation and experimental results.  相似文献   

Investigating substantive and consequential validity of student ratings of instruction     

Karma El Hassan 《高等教育研究与发展》2009,28(3):319-333

This study aimed at exploring faculty and student perspectives on student evaluations, as well as identifying their perceptions of the usefulness and appropriateness of the ratings for evaluating teaching effectiveness. More specifically, the study aimed at identifying the consequences, both intended and unintended, of using the evaluations, in addition to better understanding the process students used in responding to evaluations and what use faculty members made of them. Two surveys were developed and placed on the website of the Office of Institutional Research and Assessment. Emails were sent to all students and faculty participating in evaluations soliciting their cooperation and requesting their input. Faculty and student perceptions were compared qualitatively and statistically. Results revealed that students and faculty believe in the effectiveness and usefulness of the system with the need to overcome some negative consequences and biases inherent in its application at the University. Recommendations for system improvement are provided.  相似文献