A descriptive study and analysis of two first grade teachers\u27 development and implementation of writing-portfolio assessments.

This study is a descriptive analysis of the perceptions of selected first and second grade teachers on the design and implementation of writing-portfolio assessment. The literature supported the need to examine alternative writing assessments that include both product and process-oriented information about developing writers. Writing-portfolio assessments focus on day-to-day interactions in the classroom and provide on-going diagnostic information about students\u27 writing development and involvement with various instruction processes and procedures from one month to the next and from one year to the next. Two first grade teachers were chosen for an indepth investigation of their portfolio assessments of the early writer. Data were gathered using indepth interviewing, field observations and the analysis of student portfolios. The data collected were analyzed around categories derived from five main areas of investigation: (A) Changes in writing instruction. (B) Instruction and assessment. (C) Reporting procedures. (D) The Changing role of the teacher. (E) Support for teachers. Data gathered in this study indicated that as changes in writing instruction occurred in teachers\u27 classrooms, a need for alternative assessments developed that would focus on a closer analysis of students\u27 writing strengths and needs and would capture writing process opportunities and self-assessment activities in the classroom. As student portfolios were analyzed, teachers were able to outline patterns of strengths and needs that led to designing specific goals and implementation plans with individual students and the class as a whole. The specificity of the assessment allowed teachers to include students in self-assessment processes that focused on their development. Reporting portfolio assessment results to parents, future teachers, administrators and students themselves proved to be positive and informative. Teachers implementing writing-portfolio assessments needed time and opportunities to discuss and define good writing, determine the kinds of information to collect, articulate realistic writing goals and expectations, design appropriate implementation plans and writing strategies and organize necessary record-keeping that would document and report on progress in students\u27 writing portfolios. Student writing-portfolio assessments documented students\u27 development as writers, informed instruction and provided a window into the classroom. They offered teachers a greater potential in understanding and supporting their students\u27 literacy development

NDM-541: THE HEAT LOADS OF A TUNED MASS DAMPER

Modern tall buildings are often susceptible to excessive wind-induced motions. Tuned mass dampers (TMDs) are used to improve occupant comfort by reducing structural accelerations during common winds, and also to reduce building drift during stronger winds. A TMD is an auxiliary mass that is connected near the top of the structure through elements that produce restoring and damping forces. If the TMD is designed to have the appropriate natural frequency and damping ratio, vibrational energy from the structure is transferred to the TMD where it is dissipated through the TMD damping. This additional source of energy dissipation increases the effective damping of the building, reducing its dynamic motion. The energy dissipating elements of the TMD, whether linear or nonlinear, will convert some of the TMD’s kinetic energy into heat. It is critical that the heat generated by the TMD motion is accurately predicted, and the damping device is demonstrated to be capable of ejecting this heat. If the device cannot eject the heat it generates during operation, the device may overheat, altering its damping properties or potentially leading to device failure. This paper studies the rate of heat generation (power) of a TMD with two common forms of damping. Simple techniques are employed to calculate the mean TMD power. Nonlinear simulations are used to evaluate this simple model, and predict the peak TMD power that is expected over a short period of time. For a given structural acceleration reduction, the TMD power is independent of the form of damping

NDM-556: WIND UPLIFT RESISTANCE DESIGN OF A GREEN ROOF

Green roofs, also referred to as vegetated roofs, have increased in popularity in recent years in North America. Traditionally their use had been more prominent in European countries, such as Germany, however the North American design community have recently adopted them, thanks in part to programs such as LEED and the City of Toronto’s Green Roof Bylaw. Toronto’s Green Roof Bylaw mandates “green roofs on new commercial, institutional and residential development with a minimum Gross Floor Area of 2,000m2 as of January 31, 2010”. Also contained within the aforementioned Green Roof Bylaw is a requirement that the submitted green roof design explicitly state the uplift wind pressures that it has been designed for, and how the design addresses the stated pressures. This report needs to be stamped by a Professional Engineer. This requirement has led to many questions regarding the wind resistance of a green roof, which is a unique building material in many ways - it is organic, living, porous, and has a variable weight (based on the amount of water it is retaining). Conventional building materials have strict tolerances and highly standardized, whereas the properties of green roofs change on a daily basis. The intent of this paper is to discuss the design of a green roof in order to prevent lift off/fly away of a green roof assembly. The methods presented are based on applicable standards and building codes, as well as specific testing that has been undertaken on a green roof system to demonstrate its porosity and pressure equalization properties

STR-926: FOOTFALL-INDUCED VIBRATION: PREDICTION AND CONTROL STRATEGIES

Footfalls can produce vibrations that are irritating to occupants, or disruptive to vibration-sensitive spaces in hospitals and research laboratories. This paper describes, using case studies, techniques that can be used to predict vibrations, and mitigation strategies to control them. Firstly, pedestrian loading on footbridges is described. Stochastic simulations are conducted in which a number of pedestrians with random weights, walking speeds, and walking paths cross a bridge with random spacing. The resulting vibration response of the bridge is determined to estimate the peak acceleration of the bridge. For the case considered, tuned mass dampers (TMDs) were subsequently installed on the bridge to increase the effective damping of two modes. Next, crowd loading on stadia and ballroom structures is considered. For these structures, the crowd-structure interaction must be considered since the mass of the crowd is a significant fraction of the mass of the structure, which alters the dynamic response of the system. In the case presented, TMDs are considered to reduce the vibrations associated with crowd excitation. Lastly, the vibrations associated with a pedestrian walking in a corridor adjacent to a vibration-sensitive room in a hospital or research facility are described. Maintaining low vibrations in these hospitals and laboratories is critical as the operation of equipment may be adversely affected by vibrations that are well below the threshold of human perception. Typical mitigation strategies for these vibrations include positioning sensitive equipment near columns or increasing the stiffness or mass of the floor

Nitrogen fixation by the savanna tree Philenoptera violacea (Klotzsch) Schrire (Apple leaf) of different ages in a semi-arid riparian landscape

AbstractThe acquisition of nitrogen for growth and maintenance is essential for plants, and having multiple strategies for that acquisition is especially important for those colonizing nutrient poor substrates. Philenoptera violacea (Apple leaf) is a prominent tree in nutrient poor savanna and alluvial soils near rivers in southern Africa, where nutrient availabilities are highly variable in space and time. We investigated nitrogen fixation in P. violacea within riparian corridors flanking the Sabie River in Kruger National Park (KNP) in the Lowveld in northeastern South Africa using the natural 15N abundance technique. Results indicated that P. violacea fixes atmospheric nitrogen and this varies with life history stage. We found that foliar δ15N levels were significantly lower in all life stage classes of P. violacea compared with the reference plant D. mespiliformis growing in open riparian forest. In addition δ15N values were significantly different within the different life stages of P. violacea with the leaves of saplings and juvenile plants having significantly lower δ15N levels than mature plants. While δ15N values increased with age, foliar nitrogen concentration values declined, with leaves from sapling P. violacea having significantly higher total nitrogen than adults and juveniles, which were in turn significantly higher than juvenile D. mespiliformis. However, foliar δ15N levels in seedlings of P. violacea growing in a high nutrient environment in flood debris piles did not differ from levels recorded in seedlings of the reference tree. This study confirms that P. violacea is able to fix nitrogen, but it is dependant on soil conditions and the life stage of the trees

Fission Systems for Mars Exploration

Fission systems are used extensively on earth, and 34 such systems have flown in space. The energy density of fission is over 10 million times that of chemical reactions, giving fission the potential to eliminate energy density constraints for many space missions. Potential safety and operational concerns with fission systems are well understood, and strategies exist for affordably developing such systems. By enabling a power-rich environment and highly efficient propulsion, fission systems could enable affordable, sustainable exploration of Mars

Using the trajectory of the shuttlecock as a measure of performance accuracy in the badminton short serve

Accuracy of a projectile is typically quantified as the proportion of successful target hits, or the distance an object finishes from the target. Serving in sports such as badminton differs since the shuttlecock is usually intercepted by the opponent before landing on the target (i.e. court surface). Therefore, landing accuracy measures are inappropriate and a new method of determining accuracy of the serve is needed. During interviews, elite coaches and players described an accurate short serve as crossing the net with low clearance and having an apex before the net. Three-dimensional trajectory of the shuttlecock was therefore tracked from eight national-level players who performed 30 short serves in simulated match conditions (i.e. with an opponent); 27% of all serves were classified as ‘accurate’, 27% of serves as ‘inaccurate’, 21% with a ‘good apex’ position, and 25% with a ‘good clearance’ height. The proposed method of assessing shuttlecock trajectory as a measure of accuracy could be adopted by coaches and players to assess and improve short serve accuracy. Furthermore, this method is more representative of a match environment since the shuttlecock rarely lands because the opponent returns the serve

Fatigue does not increase limb asymmetry or induce proximal joint power shift in habitual, multi-speed runners

During prolonged jogging, joint moment and work tend to decrease in the distal (ankle) joint but increase at proximal (hip/knee) joints as performance fatigue manifests, and such adaptations might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb asymmetries, which is speculated to influence injury risk. However, the effects of fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. Using statistical parametric mapping, we compared 3-D kinematics and ground reaction force production between the dominant (DL) and non-dominant (NDL) legs of 13 soccer players during both non-fatigued and fatigued sprint running. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. DL generated higher propulsive impulse due to increased ankle work, while NDL exhibited greater vertical impulse, potentially due to greater hip flexion prior to downward foot acceleration. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantar flexion (distal-joint) moments and power. After fatiguing running, inter-limb asymmetry was reduced and no distal-to-proximal shift in joint work was detected. These adaptations may attenuate decreases in running speed whilst minimising injury risk