Understanding requirements engineering process: a challenge for practice and education

Reviews of the state of the professional practice in Requirements Engineering (RE) stress that the RE process is both complex and hard to describe, and suggest there is a significant difference between competent and "approved" practice. "Approved" practice is reflected by (in all likelihood, in fact, has its genesis in) RE education, so that the knowledge and skills taught to students do not match the knowledge and skills required and applied by competent practitioners. A new understanding of the RE process has emerged from our recent study. RE is revealed as inherently creative, involving cycles of building and major reconstruction of the models developed, significantly different from the systematic and smoothly incremental process generally described in the literature. The process is better characterised as highly creative, opportunistic and insight driven. This mismatch between approved and actual practice provides a challenge to RE education - RE requires insight and creativity as well as technical knowledge. Traditional learning models applied to RE focus, however, on notation and prescribed processes acquired through repetition. We argue that traditional learning models fail to support the learning required for RE and propose both a new model based on cognitive flexibility and a framework for RE education to support this model

Enhanced thermoelectric figure of merit in vertical graphene junctions

In this work, we investigate thermoelectric properties of junctions consisting of two partially overlapped graphene sheets coupled to each other in the cross-plane direction. It is shown that because of the weak van-der Waals interactions between graphene layers, the phonon conductance in these junctions is strongly reduced, compared to that of single graphene layer structures, while their electrical performance is weakly affected. By exploiting this effect, we demonstrate that the thermoelectric figure of merit can reach values higher than 1 at room temperature in junctions made of gapped graphene materials, for instance, graphene nanoribbons and graphene nanomeshes. The dependence of thermoelectric properties on the junction length is also discussed. This theoretical study hence suggests an efficient way to enhance thermoelectric efficiency of graphene devices.Comment: 6 pages, 4 figures, submitte

Fatigue tests on big structure assemblies of concorde aircraft

Fatigue tests on structural assemblies of the Concorde supersonic transport aircraft are reported. Two main sections of the aircraft were subjected to pressure, mechanical load, and thermal static tests. The types of fatigue tests conducted and the results obtained are discussed. It was concluded that on a supersonic aircraft whose structural weight is a significant part of the weight analysis, many fatigue and static strength development tests should be made and fatigue and thermal tests of the structures are absolutely necessary

Relationship between thoracic kyphosis and neural axis abnormalities in patients with adolescent idiopathic scoliosis.

Purpose:Previous studies have suggested an association between increased thoracic kyphosis and neural axis abnormalities in patients with adolescent idiopathic scoliosis (AIS). However, the basis for this finding is unclear, and this association has been mainly noted in retrospective studies on a non-consecutive series of patients. The purpose of this study was to assess the relationship between thoracic kyphosis and neural axis abnormalities in patients with AIS. Methods:We studied a consecutive series of AIS patients treated with spinal fusion. Thoracic kyphosis (T2 to T12) was measured from preoperative lateral radiographs. All patients underwent a spine magnetic resonance imaging (MRI) prior to surgery, and MRI reports were reviewed to determine the presence of neural axis abnormalities. Statistical analyses included descriptive statistics and chi-squared analysis. Results:This study included 210 patients with AIS. There were no significant differences in age or gender between patients with thoracic hypokyphosis (kyphosis < 20°), normal thoracic kyphosis (kyphosis 20° to 40°) and thoracic hyperkyphosis (kyphosis > 40°) (p > 0.05). Neural axis abnormalities were present in 17.9% of patients with thoracic hypokyphosis, 9.8% of patients with normal thoracic kyphosis and 13.6% of patients with thoracic hyperkyphosis (p = 0.60). There were no significant differences in rates of Chiari malformation, syrinx, intra-spinal masses and other central nervous system abnormalities between groups (p > 0.05). Conclusions:Thoracic kyphosis was not associated with neural axis abnormalities in our consecutive series of patients with AIS. Increased thoracic kyphosis may not be a reliable indicator for the presence of neural axis abnormalities in patients with AIS. Level of Evidence:IV

Mixing and Matching Learning Design and Learning Analytics

In the last five years, learning analytics has proved its potential in predicting academic performance based on trace data of learning activities. However, the role of pedagogical context in learning analytics has not been fully understood. To date, it has been difficult to quantify learning in a way that can be measured and compared. By coding the design of e-learning courses, this study demonstrates how learning design is being implemented on a large scale at the Open University UK, and how learning analytics could support as well as benefit from learning design. Building on our previous work, our analysis was conducted longitudinally on 23 undergraduate distance learning modules and their 40,083 students. The innovative aspect of this study is the availability of fine-grained learning design data at individual task level, which allows us to consider the connections between learning activities, and the media used to produce the activities. Using a combination of visualizations and social network analysis, our findings revealed a diversity in how learning activities were designed within and between disciplines as well as individual learning activities. By reflecting on the learning design in an explicit manner, educators are empowered to compare and contrast their design using their own institutional data

Finite temperature phase diagram of a spin-1 Bose gas

We formulate a self-consistent Hartree-Fock theory for a spin-1 Bose gas at finite temperature and apply it to characterizing the phase diagram. We find that spin coherence between thermal atoms in different magnetic sub-levels develops via coherent collisions with the condensed atoms, and is a crucial factor in determining the phase diagram. We develop analytical expressions to characterize the interaction and temperature dependent shifts of the phase boundaries.Comment: 11 pages, 5 figure

Correlation dynamics between Asia-Pacific, EU and US stock returns

This paper investigates the correlation dynamics in the equity markets of 13 Asia-Pacific countries, Europe and the US using the asymmetric dynamic conditional correlation GARCH model (AG-DCC-GARCH) introduced by Cappiello, Engle and Sheppard (2006). We find significant variation in correlation between markets through time. Stocks exhibit asymmetries in conditional correlations in addition to conditional volatility. Yet asymmetry is less apparent in less integrated markets. The Asian crisis acts as a structural break, with correlations increasing markedly between crisis countries during this period though the bear market in the early 2000s is a more significant event for correlations with developed markets. Our findings also provide further evidence consistent with increasing global market integration. The documented asymmetries and correlation dynamics have important implications for international portfolio diversification and asset allocation.dynamic conditional correlation; asymmetry; international portfolio diversification

Isotopic and Microstructural Analyses of Opaque Mineral Assemblages and Their Alteration Products Hosted in a Refractory Inclusion

Calcium-aluminum-rich inclusions (CAIs) hosted in primitive meteorites are the oldest solids formed in the Solar System. Some CAIs contain metal nuggets that are complex assemblages of Fe-Ni alloys, along with rare ultra-refractory metals such as platinum group elements (PGEs), and their alteration products such as magnetite, sulfides, and phosphates. Three possible mechanisms proposed to explain the origin of these metal nuggets include condensation in circumstellar settings, condensation in the solar nebula within the CAI-forming region, or crystallization from immiscible metal-silicate melt. However, secondary alteration processes may have also affected some of these assemblages. Additionally, similar metal assemblages observed in chondrules and chondritic matrix indicate that all of these metal nuggets could share common high-temperature origins. These metal assemblages record early Solar System conditions that are reflected in their distinctive chemical composition, mineralogy and microstructures. Here we report a detailed mineralogical, microstructural and oxygen isotopic study of one such metal assemblage hosted in a CAI to understand the physical and chemical settings in which it formed