Collaboration within large groups in the classroom

The purpose of this paper is to show how a large group of students can work collaboratively in a synchronous way within the classroom using the cheapest possible technological support. Making use of the features of Single Display Groupware and of Multiple Mice we propose a computer-supported collaborative learning approach for big groups within the classroom. The approach uses a multiple classification matrix and our application was built for language-learning (in this case Spanish). The basic collaboration mechanism that the approach is based upon is “silent collaboration,” in which students—through suggestions and exchanges—must compare their ideas to those of their classmates. An exploratory experimental study was performed along with a quantitative and qualitative study that analyzed ease of use of the software, described how the conditions for collaborative learning were achieved, evaluated the achievements in learning under the defined language objectives, and analyzed the impact of silent and spoken collaboration. Our initial findings are that silent collaboration proved to be an effective mechanism to achieve learning in large groups in the classroom.     

Privacy, additional information and communication

Two parties, each holding one input of a two-variable function, communicate in order to determine the value of the function. Each party wants to expose as little of its input as possible to the other party. The authors prove tight bounds on the minimum amount of information about the individual inputs that must be revealed in the computation of most functions and of some specific ones. They also show that a computation that reveals little information about the individual inputs may require many more message exchanges than a more revealing computation     

Measurement of polarization mode dispersion in systems having polarization dependent loss or gain

The principal states of polarization and their propagation characteristics are analyzed for both unitary and nonunitary optical systems in terms of the complex plane representation of polarization. A new method for the estimation of the polarization mode dispersion of the system is proposed together with experimental and simulation results.     

Advanced Testing and Characterization of Asphalt Concrete Materials in Tension

The modeling of asphalt concrete materials is currently handled using linear viscoelasticity (VE) and viscoplasticity (VP) with damage. Exploratory frequency sweep and creep and recovery test results indicate that the linear VE with damage theory cannot represent the material response unless damage–healing is also included in the formulation. Therefore, the concept of effective stress, used for modeling damage, is extended to include additional nonlinear effects. A new theory of nonlinear VE with damage and VP is presented for uniaxial loading conditions in tension. A special load transfer device is described. It allows very fast unloading and very long recovery periods with complete unloading. It permits better separation between VE and VP components. Using this device, a uniaxial tension creep and recovery test is conducted and analyzed. The nonlinear material response is illustrated and a calibration of the damage function is presented. The formulation is being extended to three-dimensional conditions.     

Self-regulated Complexity in Neural Networks

Recordings of spontaneous activity of in vitro neuronal networks reveal various phenomena on different time scales. These include synchronized firing of neurons, bursting events of firing on both cell and network levels, hierarchies of bursting events, etc. These findings suggest that networks’ natural dynamics are self-regulated to facilitate different processes on intervals in orders of magnitude ranging from fractions of seconds to hours. Observing these unique structures of recorded time-series give rise to questions regarding the diversity of the basic elements of the sequences, the information storage capacity of a network and the means of implementing calculations. Due to the complex temporal nature of the recordings, the proper methods of characterizing and quantifying these dynamics are on the time–frequency plane. We thus introduce time-series analysis of neuronal network’s synchronized bursting events applying the wavelet packet decomposition based on the Haar mother-wavelet. We utilize algorithms for optimal tiling of the time–frequency plane to signify the local and global variations within the sequence. New quantifying observables of regularity and complexity are identified based on both the homogeneity and diversity of the tiling (Hulata et al., 2004, Physical Review Letters 92: 198181–198104 ). These observables are demonstrated while exploring the regularity–complexity plane to fulfill the accepted criteria (yet lacking an operational definition) of Effective Complexity. The presented question regarding the sequences’ capacity of information is addressed through applying our observables on recorded sequences, scrambled sequences, artificial sequences produced with similar long-range statistical distributions and on outputs of neuronal models devised to simulate the unique networks’ dynamics.     

Early diagnosis of necrotizing enterocolitis

This study demonstrates that the diagnosis of necrotizing enterocolitis can sometimes be made before the full-blown clinical and radiographic findings are manifest. Of 12 infants with films available prior to diagnosis of the disease, nine had early selective dilatation of small bowel and little or no air in the colon. Necrotizing enterocolitis should be foremost in the differential diagnosis when this finding is coupled with signs such as abdominal distention, acidosis, and diarrhea.     

On the Mobile Behavior of Solid 4He at High Temperatures

We report studies of solid helium contained inside a torsional oscillator, at temperatures between 1.07 K and 1.87 K. We grew single crystals inside the oscillator using commercially pure ⁴He and ³He-⁴He mixtures containing 100 ppm ³He. Crystals were grown at constant temperature and pressure on the melting curve. At the end of the growth, the crystals were disordered, following which they partially decoupled from the oscillator. The fraction of the decoupled He mass was temperature and velocity dependent. Around 1 K, the decoupled mass fraction for crystals grown from the mixture reached a limiting value of around 35%. In the case of crystals grown using commercially pure ⁴He at temperatures below 1.3 K, this fraction was much smaller. This difference could possibly be associated with the roughening transition at the solid-liquid interface.     

LiMoSense: live monitoring in dynamic sensor networks

We present LiMoSense, a fault-tolerant live monitoring algorithm for dynamic sensor networks. This is the first asynchronous robust average aggregation algorithm that performs live monitoring, i.e., it constantly obtains a timely and accurate picture of dynamically changing data. LiMoSense uses gossip to dynamically track and aggregate a large collection of ever-changing sensor reads. It overcomes message loss, node failures and recoveries, and dynamic network topology changes. The algorithm uses a novel technique to bound variable size. We present the algorithm and formally prove its correctness. We use simulations to illustrate its ability to quickly react to changes of both the network topology and the sensor reads, and to provide accurate information.